[Federal Register Volume 66, Number 144 (Thursday, July 26, 2001)]
[Proposed Rules]
[Pages 38982-39004]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-18637]


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DEPARTMENT OF TRANSPORTATION

National Highway Traffic Safety Administration

49 CFR Part 571

[Docket No. NHTSA 2000-8572]
RIN 2127-AI33


Federal Motor Vehicle Safety Standards: Tire Pressure Monitoring 
Systems; Controls and Displays

AGENCY: National Highway Traffic Safety Administration (NHTSA), 
Department of Transportation (DOT).

ACTION: Notice of proposed rulemaking.

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SUMMARY: The Transportation Recall Enhancement, Accountability, and 
Documentation Act of 2000 mandates a rulemaking proceeding to require 
motor vehicles to be equipped with a tire pressure monitoring system 
that warns the driver a tire is significantly under-inflated. In 
response, this document proposes to establish a new Federal Motor 
Vehicle Safety Standard No. 138 that would require tire pressure 
monitoring systems to be installed in new passenger cars and in new 
light trucks and multipurpose passenger vehicles.
    This document seeks comment on two alternative versions of the new 
standard. One alternative would require that the driver be warned when 
the tire pressure in one or more tires, up to a total of 4 tires, has 
fallen to 20 percent or more below the vehicle manufacturer's 
recommended cold inflation pressure for the vehicle's tires, or a 
minimum level of pressure to be specified in the new standard, 
whichever is higher. The other alternative would require that the 
driver be warned when tire pressure in one or more tires, up to a total 
of 3 tires, has fallen to 25 percent or more below the vehicle 
manufacturer's recommended cold inflation pressure for the vehicle's 
tires, or a minimum level of pressure to be specified in the new 
standard, whichever is higher.

DATES: Comments must be received on or before September 6, 2001.

ADDRESSES: You may submit your comments in writing to: Docket Section, 
National Highway Traffic Safety Administration, 400 Seventh Street, 
SW., Washington, DC 20590. Alternatively, you may submit your comments 
electronically by logging onto the Docket Management System (DMS) 
website at http://dms.dot.gov. Click on ``Help & Information'' or 
``Help/Info'' to view instructions for filing your comments 
electronically. Regardless of how you submit your comments, you should 
mention the docket number of this document. You can find the number at 
the beginning of this document.

FOR FURTHER INFORMATION CONTACT: For non-legal issues, you may call Mr. 
George Soodoo or Mr. Joseph Scott, Office of Crash Avoidance Standards 
(Telephone: 202-366-2720) (Fax: 202-366-4329).
    For legal issues, you may call Mr. Dion Casey, Office of Chief 
Counsel (Telephone: 202-366-2992) (Fax: 202-366-3820).
    You may send mail to these officials at National Highway Traffic 
Safety Administration, 400 Seventh Street, SW., Washington, DC 20590.
    You may call Docket Management at 202-366-9324. You may visit the 
Docket from 10 a.m. to 5 p.m., Monday through Friday.

SUPPLEMENTARY INFORMATION:

Table of Contents

I. Executive Summary
II. Background
    A. The Transportation Recall Enhancement, Accountability, and 
Documentation Act
    B. Previous Rulemaking on Tire Pressure Monitoring Systems
III. Problem Description
    A. Infrequent Consumer Monitoring of Tire Pressure
    B. Loss of Tire Pressure Due to Natural and Other Causes
    C. Percentage of Motor Vehicles With Under-Inflated Tires
    D. Consequences of Under-Inflation of Tires
    1. Reduced Vehicle Safety
    2. Reduced Tread Life
    3. Reduced Fuel Economy
IV. Tire Pressure Monitoring Systems
    A. Indirect TPMSs
    B. Direct TPMSs
    C. Advantages and Disadvantages
    1. Indirect TPMSs
    2. Direct TPMSs
    3. Tabular Summary of Advantages and Disadvantages of Indirect 
and Direct TPMSs
V. Agency Proposal
    A. Summary of Proposal
    B. Vehicles Covered by This Proposal
    C. Definition of ``Significantly Under-Inflated''
    D. Low Tire Pressure Warning Telltale
    1. Color
    2. Symbol
    3. Time Frame for Telltale Illumination
    4. Duration of Warning
    5. Self-Check
    E. System Calibration and Reset
    F. System Failure
    G. Number of Tires Monitored
    H. Replacement Tires/Rims
    I. Monitoring of Spare Tire
    J. Written Instructions
    K. Temperature Compensation
    L. Test Conditions
    M. Test Procedures
    N. Human Factors
VI. Benefits
    A. First Alternative

[[Page 38983]]

    B. Second Alternative
    C. Unquantified Benefits
VII. Costs
    A. Indirect TPMSs
    B. Direct TPMSs
    C. Testing and Maintenance Costs
    D. Unquantified Costs
    E. First Alternative
    F. Second Alternative
VIII. Lead-Time
IX. Rulemaking Analyses and Notices

I. Executive Summary

    This document proposes to establish a new Federal Motor Vehicle 
Safety Standard that would require tire pressure monitoring systems 
(TPMSs) to be installed in new passenger cars and in new light trucks 
and multipurpose passenger vehicles. Each vehicle's system would 
include a warning telltale that illuminates to inform the driver when 
the vehicle has a significantly under-inflated tire.
    This document seeks comment on two alternative versions of the new 
standard. One alternative would require that the driver be warned when 
the tire pressure in one or more tires, up to a total of 4 tires, has 
fallen to 20 percent or more below the vehicle manufacturer's 
recommended cold inflation pressure for the vehicle's tires, or a 
minimum level of pressure to be specified in the new standard, 
whichever pressure is higher. The other alternative would require that 
the driver be warned when tire pressure in one or more tires, up to a 
total of 3 tires, has fallen to 25 percent or more below the vehicle 
manufacturer's recommended cold inflation pressure for the vehicle's 
tires, or a minimum level of pressure to be specified in the new 
standard, whichever pressure is higher.
    To meet the first alternative, vehicle manufacturers would likely 
need to install direct TPMSs. Direct TPMSs have a tire pressure sensor 
in each tire.
    To meet the second alternative, vehicle manufacturers could install 
either direct or indirect TPMSs. Indirect TPMSs do not have tire 
pressure sensors. Current indirect TPMSs rely on the presence of an 
anti-lock braking system (ABS) to detect and compare differences in the 
rotational speed of a vehicle's wheels. Wheel speed correlates to tire 
pressure since the diameter of a tire decreases slightly as tire 
pressure decreases. The second alternative would require only warnings 
about pressure loss in up to three tires since most indirect TPMSs 
cannot detect when all four tires lose pressure at roughly the same 
rate and become significantly under-inflated.
    NHTSA anticipates that vehicle manufacturers would minimize their 
costs of complying with the second alternative by installing indirect 
TPMSs in vehicles currently equipped with ABSs and direct TPMSs in 
vehicles currently not so equipped. For vehicles already equipped with 
an ABS, the cost of modifying that system to serve the additional 
purpose of indirectly monitoring tire pressure would be significantly 
less than the cost of adding a direct TPMS to those vehicles. For 
vehicles not so equipped, adding a direct TPMS would be the less 
expensive way of monitoring tire pressure.
    NHTSA has two sets of data, one from Goodyear and another from the 
agency's Vehicle Research and Testing Center (VRTC), on the effect of 
under-inflated tires on a vehicle's stopping distance. The Goodyear 
data indicate that a vehicle's stopping distance on wet surfaces is 
significantly reduced when its tires are properly inflated, as compared 
to when its tires are significantly under-inflated. The VRTC data 
indicate little or no effect on a vehicle's stopping distance. For 
purposes of this rulemaking, NHTSA is using the Goodyear data to 
establish an upper bound of benefits and the VRTC data to establish a 
lower bound. The estimates below are the mid-points between those upper 
and lower bounds.
    NHTSA estimates that the first alternative would prevent 10,635 
injuries and 79 deaths at an average cost of $66.33 per vehicle.\1\ 
Since approximately 16 million vehicles are produced for sale in the 
United States each year, the total annual cost of the first alternative 
would be about $1.06 billion. However, if the average per vehicle fuel 
and tread life savings ($32.22 and $11.03, respectively) over the 
lifetime of the vehicle are factored in, the average net cost of the 
first alternative drops to $23.08 per vehicle, and the total annual 
cost drops to about $369 million ($1.06 billion-($516 million + $176 
million)) . The second alternative would prevent 6,585 injuries and 49 
deaths at an average cost of $30.54 per vehicle.\2\ Since approximately 
16 million vehicles are produced for sale in the United States each 
year, the total annual cost of the second alternative would be about 
$489 million. However, if the average per vehicle fuel and tread wear 
savings ($16.40 and $5.51, respectively) over the lifetime of the 
vehicle are factored in, the average net cost of the second alternative 
drops to $8.63 per vehicle, and the total annual cost drops to about 
$138 million ($489 million-($263 million + 88 million). The net cost 
per equivalent life saved would be $1.9 million for the first 
alternative and $1.1 million for the second.
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    \1\ The range of injuries prevented would be 0 to 21,270, an the 
range of deaths prevented would be 0 to 158.
    \2\ The range of injuries prevented would be 0 to 13,170, an the 
range of deaths prevented would be 0 to 97.
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    The agency believes the proposals would also result in other 
benefits, such as fewer crashes resulting from tire blowouts, adverse 
effects on vehicle handling due to inflation pressure loss and 
hydroplaning, from fewer crashes involving vehicles that had been 
stopped by the side of the road because of a flat tire, and the 
prevention of the property damage that results from these crashes. 
NHTSA has not attempted to quantify those benefits. Those unquantified 
benefits would be greater for the first alternative than the second 
alternative.
    The agency believes the proposals may also result in additional 
costs, such as the cost of replacing worn or damaged TPMS equipment and 
the cost of the time it would take for a driver to react to a low tire 
pressure warning by pulling over to a gas station to check and inflate 
the vehicle's tires. NHTSA has not attempted to quantify those costs.

II. Background

A. The Transportation Recall Enhancement, Accountability, and 
Documentation Act

    Congress enacted the Transportation Recall Enhancement, 
Accountability, and Documentation (TREAD) Act on November 1, 2000.\3\ 
Section 13 of the TREAD Act mandates ``a rulemaking for a regulation to 
require a warning system in new motor vehicles to indicate to the 
operator when a tire is significantly under inflated'' within one year 
of the TREAD Act's enactment. Section 13 also provides that the 
regulation must take effect within two years of the completion of the 
rulemaking.
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    \3\ Public Law 106-414.
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B. Previous Rulemaking on Tire Pressure Monitoring Systems

    NHTSA first considered requiring a ``low tire pressure warning 
device'' in 1970. However, the agency determined that only warning 
device then available was an in-vehicle indicator, and that its cost 
was too high.
    During the 1970s, several manufacturers developed inexpensive on-
tire warning devices. In addition, the price of in-vehicle warning 
devices dropped significantly.
    On January 26, 1981, NHTSA published an Advanced Notice of Proposed 
Rulemaking (ANPRM)

[[Page 38984]]

soliciting public comment on whether the agency should propose a new 
Federal motor vehicle safety standard requiring each new motor vehicle 
to have a low tire pressure warning device which would ``warn the 
driver when the tire pressure in any of the vehicle's tires was 
significantly below the recommended operating levels.'' (46 FR 8062).
    NHTSA noted in the ANPRM that under-inflated tires increase the 
rolling resistance of vehicles and, correspondingly, decrease their 
fuel economy. Research data at the time indicated that radial tires 
under-inflated by 10 pounds per square inch (psi) reduced the fuel 
economy of the vehicle on which they were mounted by 3 percent. Because 
of the worldwide oil shortages in the late 1970s and early 1980s, NHTSA 
was interested in finding ways to increase the fuel economy of 
passenger vehicles (i.e., passenger cars and multipurpose passenger 
vehicles). Since surveys conducted by the agency showed that about 50 
percent of passenger car tires and 13 percent of truck tires were 
operated at pressures below the vehicle manufacturers' recommended 
inflation levels, the agency believed that low tire pressure warning 
devices would encourage drivers to maintain their tires at the proper 
inflation level, thus maximizing their vehicles' fuel economy.
    Moreover, a 1973 study by Indiana University concluded that under-
inflated tires were a probable cause of 1.4 percent of all motor 
vehicle crashes.\4\ Based on that figure, and the approximately 18.3 
million motor vehicle crashes then occurring annually in the U.S., the 
agency suggested that under-inflated tires were probably responsible 
for 260,000 crashes each year (1.4 percent  x  18.3 million crashes).
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    \4\ Indiana Tri-Level Study of the Causes of Traffic Accidents, 
1973.
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    In the ANPRM, the agency sought answers from the public to several 
questions, including:
    (1) What tire pressure level should trigger the warning device?
    (2) Should the agency specify the type of warning device (i.e., on-
tire, in-vehicle) to be used?
    (3) What would it cost to produce and install an on-tire or in-
vehicle warning device?
    (4) What is the fuel saving potential of low tire pressure warning 
devices?
    (5) What studies have been performed which would show cause and 
effect relationships between low tire pressure and auto crashes?
    (6) What would be the costs and benefits of a program to educate 
the public on the benefits of maintaining proper tire pressure?
    NHTSA terminated the rulemaking on August 31, 1981. (46 FR 43721, 
August 31, 1981). The agency did so because public comments on the 
ANPRM indicated that the low tire pressure warning devices available at 
the time either had not been proven to be accurate and reliable or were 
too expensive. The comments indicated that in-vehicle warning devices 
had been proven to be accurate and reliable, but would have had a 
retail cost of $200 (in 1981 dollars) per vehicle. NHTSA stated, ``Such 
a cost increase cannot be justified by the potential benefits, although 
those benefits might be significant.'' (46 FR 43721). The comments also 
indicated that on-tire warning devices cost only about $5 (in 1981 
dollars) per vehicle, but they had not been developed to the point 
where they were accurate and reliable enough to be required. The 
comments also suggested that on-tire warning devices were subject to 
road hazards, such as scuffing at curbs, ice, mud, etc. However, NHTSA 
said that it still believed that ``[m]aintaining proper tire inflation 
pressure results in direct savings to drivers in terms of better gas 
mileage and longer tire life, as well as offering increased safety.'' 
(46 FR 43721).

III. Problem Description

    Drivers' infrequent monitoring of their vehicles' tire pressure, 
combined with the difficulty of visually detecting when a tire is 
several psi below the recommended inflation pressure and with typical 
tire pressure losses due to natural leakage and seasonal climatic 
changes, contribute to many vehicles' having under-inflated tires.

A. Infrequent Consumer Monitoring of Tire Pressure

    Surveys have shown that most drivers infrequently check the 
inflation pressure in their vehicles' tires. One such survey was the 
omnibus survey conducted by the Bureau of Transportation Statistics 
(BTS) in September 2000 for NHTSA. The BTS conducted 1,017 household 
interviews. One of the questions posed was: ``How often do you, or the 
person who checks your tires, check the air pressure in your tires?'' 
The answers indicated that 29 percent of the respondents stated that 
they check the air pressure in their tires monthly; 29 percent stated 
that they check the air pressure only when one or more of their 
vehicle's tires appears under-inflated; 19 percent stated that they 
only have the air pressure checked when the vehicle is serviced; 5 
percent stated that they only check the air pressure before taking 
their vehicle on a long trip; and 17 percent stated that they check the 
air pressure on some other occasion. Thus, 71 percent of drivers stated 
that they check the air pressure in their vehicles' tires less than 
once a month.\5\
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    \5\ The agency notes that it seems likely that the respondents 
overstated the frequency with which they check tire pressure, 
particularly given the fact that this survey was conducted during 
the height of publicity in the fall of 2000 about tire failures on 
sport utility vehicles.
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    In addition, NHTSA's National Center for Statistics and Analysis 
(NCSA) conducted a survey in February 2001. The survey was designed to 
assess the extent to which passenger vehicle drivers are aware of the 
recommended air pressure for their tires, if they monitor air pressure, 
and to what extent actual tire pressure differs from that recommended 
by the vehicle manufacturer.
    Data was collected through the infrastructure of the National 
Accident Sampling System--Crashworthiness Data System (NASS-CDS). The 
NASS-CDS consists of 24 Primary Sampling Units (PSUs) located across 
the country. Within each PSU, a random selection of zip codes was 
obtained from a list of eligible zip codes. Within each zip code, a 
random selection of two gas stations was obtained.
    A total of 11,530 vehicles were inspected at these gas stations. 
This total comprised 6,442 passenger cars, 1,874 SUVs, 1,376 vans, and 
1,838 pick-up trucks. For analytical purposes, the data were divided 
into three categories: (1) passenger cars with P-metric tires; (2) 
pick-up trucks, SUVs, and vans with P-metric tires; and (3) pick-up 
trucks, SUVs, and vans with either light truck (LT) or flotation tires.
    Drivers were asked how often they normally check their tires to 
determine if they are properly inflated. Their answers are in the 
following table:

[[Page 38985]]



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                                                             Drivers of      Drivers of pick-up trucks, SUVs and
                                                           passenger cars                 vans  (%)
          How often is tire pressure checked?                   (%)        -------------------------------------
                                                        -------------------                     LT or flotation
                                                           P-metric tires     P-metric tires         tires
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Weekly.................................................               8.76               8.69               8.16
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Monthly................................................              21.42              25.19              39.88
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When they seem low.....................................              25.63              23.58              15.59
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When serviced..........................................              30.18              27.72              25.54
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For long trip..........................................               0.99               2.39               2.17
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Other..................................................               6.46               8.27               6.97
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Do not check...........................................               6.56               4.16               1.69
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    These data indicate that only about 30 percent of drivers of 
passenger cars, 34 percent of drivers of pick-up trucks, SUVs, and vans 
with P-metric tires, and 48 percent of drivers of pick-up trucks, SUVs, 
and vans with either LT or flotation tires claim that they check the 
inflation level in their tires at least once a month.

B. Loss of Tire Pressure Due to Natural and Other Causes

    According to data from the tire industry, 85 percent of all tire 
air pressure losses are the result of slow leaks that occur over a 
period of hours, days, or months. Only 15 percent of tire air pressure 
losses are rapid air losses caused by contact with a road hazard, e.g., 
when a tire is punctured by a large nail that does not end up stuck in 
the tire. Slow leaks may be caused by many factors. Tires typically 
lose air pressure through natural leakage and permeation at a rate of 1 
pound per square inch (psi) per month. In addition, seasonal climatic 
changes result in air pressure losses on the order of 1 psi for every 
10 deg.F decrease in the ambient temperature. Slow leaks also may be 
caused by slight damage to a tire, such as a road hazard that punctures 
a small hole in the tire or a nail that sticks in the tire. The agency 
has no data indicating how often any of these causes results in a slow 
leak.

C. Percentage of Motor Vehicles With Under-Inflated Tires

    During the tire pressure survey, NASS-CDS crash investigators 
measured tire pressure on each vehicle coming into the gas station and 
compared the measured pressures to the vehicle manufacturer's 
recommended tire pressure. They found that about 36 percent of 
passenger cars and about 40 percent of light trucks had at least one 
tire that was at least 20 percent below the vehicle manufacturer's 
recommended cold inflation pressure. About 26 percent of passenger cars 
and 29 percent of light trucks had at least one tire that was at least 
25 percent below the vehicle manufacturer's recommended cold inflation 
pressure. The agency notes those levels of under-inflation because they 
are the threshold levels at which the low tire pressure warning 
telltale would have to be illuminated in the two alternatives proposed 
in this NPRM.

D. Consequences of Under-Inflation of Tires

1. Reduced Vehicle Safety
    When a tire is used while significantly under-inflated, its 
sidewalls flex more and the air temperature inside it increases, making 
the tire more prone to failure. In addition, a significantly under-
inflated tire loses lateral traction, making handling more difficult. 
The agency also has received data from Goodyear indicating that 
significantly under-inflated tires increase a vehicle's stopping 
distance on wet surfaces.
    NHTSA's crash files do not contain any direct evidence that points 
to low tire pressure as the cause of any particular crash. However, 
this lack of data does not imply that low tire pressure does not cause 
or contribute to any crashes. It simply reflects the fact that 
measurements of tire pressure are not among the vehicle information 
included in the crash reports received by the agency and placed in its 
crash data bases.\6\
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    \6\ These crash data bases are the National Automotive Sampling 
System--Crashworthiness Data System (NASS-CDS) and the Fatality 
Analysis Reporting System (FARS).
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    The only tire-related data element in the agency's data bases is 
``flat tire or blowout.'' Even in crashes for which a flat tire or 
blowout is reported, crash investigators cannot tell whether low tire 
pressure contributed to the tire failure.
    The agency examined its crash files to gather information on tire-
related problems that resulted in crashes. The National Automotive 
Sampling System--Crashworthiness Data System (NASS-CDS) has trained 
investigators who collect data on a sample of tow-away crashes around 
the United States. These data can be weighted to generate national 
estimates.
    The NASS-CDS General Vehicle Form contains a value indicating 
vehicle loss of control due to a blow out or flat tire. This value is 
used only when a vehicle's tire went flat, causing a loss of control of 
the vehicle and a crash. The value is not used for cases in which one 
or more of a vehicle's tires was under-inflated, preventing the vehicle 
from performing as well as it could have in an emergency situation.
    NHTSA examined NASS-CDS data for 1995 through 1998 and estimated 
that 23,464 tow-away crashes, or one-half of one percent of all 
crashes, are caused by blowouts or flat tires each year. This is 
significantly fewer crashes than estimated by the 1973 Indiana Tri-
Level study. However, the 260,000 crashes estimated in that study 
represented all crashes in which under-inflation was a probable or 
possible cause. The 23,464 crashes estimated from the NASS-CDS data are 
tow-away crashes caused by tire failure only. Further, in 1977, only 12 
percent of vehicles were equipped with radial tires, while today over 
90 percent of vehicles are equipped with radial tires. Radial tires are 
much more structurally sound than the bias-ply tires that were widely 
used in 1977. Thus, the current estimate of 23,464 crashes and the 1977 
estimate of 260,000 crashes are not comparable.

[[Page 38986]]

    The agency placed the tow-away crashes from the NASS-CDS files into 
two categories: Passenger car crashes and light truck crashes. 
Passenger cars were involved in 10,170 of the tow-away crashes caused 
by blowouts or flat tires, and light trucks were involved in the other 
13,294.
    NHTSA also examined data from the Fatality Analysis Reporting 
System (FARS) for evidence of tire problems involved in fatal crashes. 
In FARS, if tire problems are noted after the crash, the simple fact of 
their existence is all that is noted. No attempt is made to ascribe a 
role in the crash to those problems. Thus, the agency does not know 
whether the noted tire problem caused the crash, influenced the 
severity of the crash, or simply occurred during the crash. For 
example, a tire may have blown out and caused the crash, or a tire may 
have blown out during the crash when the vehicle struck some object 
such as a curb.
    Thus, while an indication of a tire problem in the FARS file gives 
some clue as to the potential magnitude of tire problems in fatal 
crashes, the FARS data cannot give a precise measure of the causal role 
played by those problems. The very existence of tire problems are 
sometimes difficult to detect and to code accurately. Further, coding 
practices vary from State to State. Nevertheless, the agency notes 
that, from 1995 to 1998, 1.10% of all light vehicles involved in fatal 
crashes were coded as having tire problems. Over 535 fatal crashes 
involved vehicles coded with tire problems.
    Under-inflated tires can contribute to other types of crashes than 
those resulting from blow outs or tire failure, including crashes which 
result from: an increase in stopping distance; skidding and/or a loss 
of control of the vehicle in a curve or in a lane change maneuver; or 
hydroplaning on a wet surface. However, the agency does not have any 
data on how often under-inflated tires cause crashes or contribute to 
their occurrence.
    Tires are designed to perform at a specific inflation pressure. 
When a tire is under-inflated, the shape of its footprint and the 
pressure it exerts on the road surface are both altered. One 
consequence of this alteration can be a reduction in the tire's ability 
to transmit (or generate) braking force to the road surface, at least 
on wet surfaces.\7\ Thus, under-inflated tires may increase a vehicle's 
stopping distance on wet surfaces. This is discussed more fully in the 
Benefits section below.
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    \7\ On dry surfaces, stopping distance seems to be only mildly 
affected by inflation pressure. Thomas D. Gillespie, Fundamentals of 
Vehicle Dynamics, Society of Automotive Engineers, 1992, p. 57.
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2. Reduced Tread Life
    Unpublished data submitted by Goodyear indicate that when a tire is 
under-inflated, more pressure is placed on the shoulders of the tire, 
causing the tread to wear incorrectly. The Goodyear data also indicated 
that the tread on an under-inflated tire wears more rapidly than it 
would if the tire were inflated to the proper pressure. The agency 
requests comment on this issue.
    The Goodyear data indicate that the average tread life of a tire is 
45,000 miles, and the average cost of a tire is $61 (in 2000 dollars). 
Goodyear also estimated that a tire's average tread life would drop to 
68 percent of the expected tread life if tire pressure dropped from 35 
psi to 17 psi and remained there. Goodyear also assumed that this 
relationship was linear. Thus, for every 1 psi drop in tire pressure, 
tread life would decrease by 1.78 percent (32 percent/18). This loss of 
tread life would take place over the lifetime of the tire. Thus, 
according to Goodyear's data, if the tire remained under-inflated by 1 
psi over its lifetime, its tread life would decrease by about 800 miles 
(1.78 percent of 45,000 miles).
    As noted above, data from the NCSA tire pressure survey show that 
36 percent of passenger cars had at least one tire that was under-
inflated by at least 20 percent. The average level of under-inflation 
of the four tires on these cars was 6.1 psi. Thus, on average, 
passenger cars could lose about 4,880 miles (6.1 psi  x  800 miles) of 
tire life due to under-inflation, if their tires were under-inflated to 
that extent throughout the life of the tires.
    As also noted above, data from the NCSA tire pressure survey also 
show that about 40 percent of light trucks had at least one tire that 
was under-inflated by at least 20 percent. The average level of under-
inflation of the four tires on these light trucks was 7.7 psi. Thus, on 
average, those light trucks could lose about 6,160 miles (7.7 psi  x  
800 miles) of tire life due to under-inflation, if their tires were 
under-inflated to that extent throughout the life of the tires.
3. Reduced Fuel Economy
    Under-inflated tires increase the rolling resistance of vehicles 
and, correspondingly, decrease their fuel economy. According to a 1978 
report,\8\ fuel efficiency is reduced by one percent for every 3.3 psi 
of under-inflation. More recent data provided by Goodyear indicate that 
fuel efficiency is reduced by one percent for every 2.96 psi of under-
inflation.
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    \8\ The Aerospace Corporation, Evaluation of Techniques for 
Reducing In-use Automotive Fuel Consumption, June 1978.
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    NHTSA notes that there is an apparent conflict between the Goodyear 
data indicating under-inflated tires increase a vehicle's stopping 
distance and the data indicating under-inflated tires increase a 
vehicle's rolling resistance. Since an under-inflated tire typically 
has a larger tread surface area (i.e., tire footprint) in contact with 
the road, the vehicle should have more traction, and its stopping 
distance should be reduced.
    The larger footprint does result in an increase in rolling 
resistance on dry road surfaces due to increased friction between the 
tire and the road surface. However, the larger tire footprint also 
reduces the tire load per unit area. On dry road surfaces, the 
countervailing effects of a larger footprint and reduced load per unit 
of area nearly offset each other, with the result that the vehicle's 
stopping distance performance is only mildly affected by under-
inflation.
    On wet surfaces, however, under-inflation typically increases 
stopping distance for several reasons. First, as noted above, the 
larger tire footprint provides less tire load per area than a smaller 
footprint. Second, since the limits of adhesion are lower and achieved 
earlier on a wet surface than on a dry surface, a tire with a larger 
footprint, given the same load, is likely to slide earlier than the 
same tire with a smaller footprint because of the lower load per 
footprint area. The rolling resistance of an under-inflated tire on a 
wet surface is greater than the rolling resistance of the same tire 
properly-inflated on the same wet surface. This is because the slightly 
larger tire footprint on the under-inflated tire results in more rubber 
on the road and hence more friction to overcome. However, the rolling 
resistance of an under-inflated tire on a wet surface is less than the 
rolling resistance of the same under-inflated tire on a dry surface 
because of the reduced friction caused by the thin film of water 
between the tire and the road surface. The less tire load per area and 
lower limits of adhesion of an under-inflated tire on a wet surface are 
enough to overcome the increased friction caused by the larger 
footprint of the under-inflated tire. Hence, under-inflated tires cause 
longer stopping distance on wet surfaces than properly-inflated tires.

IV. Tire Pressure Monitoring Systems

    There are two types of tire pressure monitoring systems (TPMSs). 
Direct systems directly measure the pressure in

[[Page 38987]]

a vehicle's tires, while indirect ones estimate the pressure. Both 
types inform the driver when the pressure in one or more tires falls 
below a pre-determined level. Unless the TPMS is connected to an 
automatic inflation system, the driver must stop the vehicle and 
inflate the under-inflated tire(s), preferably to the pressure 
recommended by the vehicle manufacturer. Currently, TPMSs are available 
as original equipment on a few vehicle models. They are available also 
as after-market equipment, but few are sold.
    NHTSA's Vehicle Research and Test Center (VRTC) evaluated six 
direct and four indirect TPMSs that are currently available.\9\ The 
VRTC found that the direct TPMSs were accurate to within an average of 
 1.0 psi, and indirect systems were accurate to within an 
average of  1.1 psi.\10\ This leads the agency to believe 
that current TPMSs are more accurate than the systems that were 
available at the time of the agency's 1981 rulemaking on TPMSs.
---------------------------------------------------------------------------

    \9\ An Evaluation of Existing Tire Pressure Monitoring Systems, 
May 2001. A copy of this report is available in the docket.
    \10\ This is not to say that the systems were able to detect a 
1.0 psi drop in pressure. The systems were accurate within 
1.0 to 1.1 psi once tire pressure had fallen by a 
certain percentage.
---------------------------------------------------------------------------

    Following is a description of the two types of TPMSs and their 
advantages and disadvantages.

A. Indirect TPMSs

    Indirect TPMSs typically work with the vehicle's anti-lock brake 
system (ABS). The ABS employs wheel speed sensors to measure the 
rotational speed of each of the four wheels. As a tire's pressure 
decreases, the rolling radius decreases, and the rotational speed of 
that wheel increases correspondingly. Most indirect TPMSs compare each 
wheel's rotational speed with the rotational speed of the other wheels. 
If one tire becomes significantly under-inflated while the others 
remain at the proper pressure, the indirect TPMS can detect it because 
that wheel's rotational speed is higher than the rotational speed of 
the other wheels. This information is conveyed to the driver by a 
simple telltale. The telltale indicates that a tire is under-inflated, 
but cannot identify which tire is under-inflated. Current vehicles that 
have indirect systems include the Toyota Sienna, Ford Windstar, and 
Oldsmobile Alero.

B. Direct TPMSs

    Direct TPMSs use pressure sensors, located in each wheel, to 
directly measure the pressure in each tire. These sensors broadcast 
data via a wireless radio frequency transmitter to a central receiver 
which analyzes the data. The central receiver is connected to a display 
mounted inside the vehicle. The type of display varies from a simple, 
single telltale to a display showing the pressure and temperature in 
each tire, sometimes including the spare tire. Thus, direct TPMSs can 
be linked to a display that tells the driver which tire is under-
inflated. An example of a vehicle equipped with a direct system is the 
Chevrolet Corvette.

C. Advantages and Disadvantages

1. Indirect TPMSs
    Indirect TPMSs have several advantages. First, they are less 
expensive than direct TPMSs for vehicles already equipped with an ABS. 
If a vehicle is already equipped with an ABS, the vehicle's 
manufacturer will only have to add the capability to monitor the wheel 
speed sensors, a low tire pressure warning telltale, and a reset 
button, and make some software changes. Making these additions and 
changes in a way that produces indirect systems like those currently on 
motor vehicles would cost about $12.90 per vehicle. However, as 
explained below, the agency is uncertain whether such an indirect TPMS 
would comply with either of the alternatives proposed in this NPRM.
    NHTSA tested four current ABS-based indirect TPMSs. None of the 
four met the proposed requirements for either alternative. These TPMSs 
had problems detecting two significantly under-inflated tires on the 
same axle and on the same side of the vehicle. They also did not 
illuminate the low tire pressure warning telltale when the pressure in 
the vehicle's tires decreased to 20 percent, or even 25 percent, below 
the vehicle manufacturer's recommended cold inflation pressure. NHTSA 
does not know whether improving current indirect TPMSs to meet the 
requirements of either alternative would result in additional costs. 
The agency requests comments on this issue.
    Pickup trucks comprise about 40 percent of light truck sales. Some 
percentage of pickup trucks that have ABS have only one wheel speed 
sensor for the rear axle. In order to meet the requirements of either 
proposed alternative, NHTSA believes vehicle manufacturers would have 
to add a fourth wheel speed sensor to these trucks at an estimated cost 
of $20 per vehicle. The agency assumes for this analysis that about 10 
percent of all light trucks, or 7.5 percent of all light vehicles with 
ABS, would be in this category. However, the agency requests comment on 
the percentage of pickup trucks that would need this modification.
    For vehicles currently without ABS, there are two indirect 
measurement choices. First, the vehicle manufacturer could add ABS and 
the necessary TPMS features to the vehicle. NHTSA estimates that this 
would cost about $240 per vehicle. The agency does not expect 
manufacturers to make this choice unless they are already planning for 
other reasons to add ABS. Second, the vehicle manufacturer could add 
wheel speed sensors and the necessary TPMS features to the vehicle. 
NHTSA estimates that this approach would cost about $130 per vehicle.
    Second, the wheel components of indirect TPMSs are more robust and 
less likely to sustain damage than the wheel components of direct 
TPMSs. The wheel speed sensors of indirect TPMSs are located behind the 
brakes and often are integrated into the wheel hub assembly. This 
generally shields them from road damage. In addition, the entire brake/
hub assembly would rarely be removed. In contrast, the pressure sensors 
of direct TPMSs are located inside the tire/wheel cavity, potentially 
subjecting them to road damage. These sensors also may be subject to 
damage during tire maintenance, i.e., rotating or changing the tires.
    Finally, indirect TPMSs do not need an independent power source. 
They are powered by the car's battery.
    Indirect TPMSs also have several disadvantages. First, since most 
indirect TPMSs calculate tire pressure by comparing the wheel speeds, 
they cannot detect the loss of pressure if all four tires lose pressure 
at similar rates. In its evaluation of four indirect TPMSs, the VRTC 
found that none of them were able to detect when all four of the 
vehicle's tires were equally under-inflated. The VRTC also found that 
none of the indirect TPMSs were able to detect when two tires on the 
same axle or two tires on the same side of the vehicle were equally 
under-inflated.
    Second, most indirect TPMSs cannot detect small pressure losses. 
The VRTC found that since reductions in tire diameter with reductions 
in pressure are very slight in the 15-40 psi range, most indirect TPMSs 
require a 20 to 30 percent drop in pressure before they are able to 
detect under-inflation. The VRTC also found that those thresholds were 
highly dependent on tire and loading factors.
    Third, vehicles must be moving for indirect TPMSs to detect an 
under-inflated tire. Thus, if a vehicle's tire is already under-
inflated when a person gets in and begins to drive that vehicle, an 
indirect TPMS will not be able to

[[Page 38988]]

alert the driver until after the vehicle begins moving.
    Fourth, most indirect TPMSs need substantial time to calibrate the 
system, i.e., to ``learn'' the variables associated with distinct tire 
types under varying driving conditions. The VRTC found that the four 
indirect TPMSs it evaluated took anywhere from several minutes to 
several hours to calibrate. Calibration is necessary when a vehicle is 
first driven. Recalibration is necessary when the pressure in a tire is 
changed and when the tires are rotated or replaced. Indirect TPMSs do 
not indicate that the system is in calibration mode. During the 
calibration mode, the system is not monitoring tire pressure. Thus, if 
one or more tires becomes significantly under-inflated while the system 
is calibrating, the driver would not be alerted. Moreover, the agency 
notes that the calibration process is prone to human error. For 
example, a driver may accidentally press the reset button when one or 
more of the vehicle's tires is under-inflated, but not under-inflated 
enough to illuminate the low tire pressure warning telltale. This would 
re-calibrate the system so that it accepts the under-inflated condition 
as normal. The indirect TPMS then would not be able to detect an under-
inflated tire until one or more tires was even more under-inflated than 
it already was. The agency requests comments specifically addressing 
the issue of human error that may occur with indirect TPMSs.
    Fifth, apart from the time needed to calibrate, indirect TPMSs also 
need several minutes to detect an under-inflated tire. The VRTC found 
that the four indirect TPMSs it evaluated took one to ten minutes to 
detect an under-inflated tire.
    Sixth, indirect TPMSs cannot tell the driver which tire is under-
inflated.
    Seventh, indirect TPMSs sometimes incorrectly indicate that a 
vehicle has an under-inflated tire when the vehicle is being driven on 
gravel or bumpy roads, is being driven at high speeds, e.g., over 70 
mph, or has mismatched tires or a tire that is out of balance or out of 
alignment.
2. Direct TPMSs
    Direct TPMSs have several advantages. First, since direct TPMSs 
actually measure the pressure in each tire, they are able to detect 
when any tire or combination of tires is under-inflated, including when 
all four of the vehicle's tires are equally under-inflated.
    Second, since most direct TPMSs are battery-operated, they can 
operate while the vehicle is stationary. Thus, if a vehicle's tire 
becomes significantly under-inflated while the vehicle is parked, a 
direct TPMS can alert the driver as soon as he or she starts the 
vehicle.
    Third, direct TPMSs can detect small pressure losses. Some systems 
can detect a drop in pressure as small as 1 psi.
    Fourth, direct TPMSs can be linked to a display that tells the 
driver which tire is under-inflated and the actual pressure in each 
tire.
    Fifth, direct TPMSs will not give false positives if the vehicle is 
being driven on gravel or bumpy roads, or has mismatched tires or a 
tire that is out of balance or out of alignment.
    Direct TPMSs also have disadvantages. First, they are more 
expensive than indirect TPMSs for vehicles already equipped with ABS. 
There are two main costs associated with direct TPMSs: sensors and a 
receiver. There is a wide disparity in costs for sensors, depending on 
what type of information is sensed.\11\ Providing only pressure 
sensors, as proposed to be required by both alternatives proposed in 
this NPRM, would cost from $5 to $10 per wheel, or $20 to $40 per 
vehicle.
---------------------------------------------------------------------------

    \11\ For example, some sensors sense temperature in addition to 
pressure.
---------------------------------------------------------------------------

    The costs associated with a receiver depend upon whether the 
vehicle already has a receiver capable of receiving and processing the 
information coming from the sensors. NHTSA estimates that about 60 
percent of vehicles currently have such a receiver. Making some 
software changes and adding a display showing the pressure for each 
tire would cost about $25 per vehicle. The 40 percent of vehicles 
without such a receiver would have to be equipped with a receiver 
incorporating the necessary software and with the display. The agency 
estimates that this would cost about $40 to $50 per vehicle.
    The agency estimates that the total cost of adding a direct TPMS to 
a vehicle that is already equipped with a receiver would be $49 to 
$69.\12\ For a vehicle that is not already equipped with a receiver, 
the cost would be $64 to $94. This is more than the cost of adding an 
indirect TPMS to a vehicle already equipped with an ABS, but less than 
the cost of adding wheel speed sensors or an ABS and an indirect TPMS 
to a vehicle not already equipped with an ABS.
---------------------------------------------------------------------------

    \12\ These figures include about $4 per vehicle for the cost of 
actually installing the direct TPMS.
---------------------------------------------------------------------------

    Second, the wheel components of direct TPMSs are less robust and 
more likely to sustain damage than the wheel components of indirect 
TPMSs, especially when tires are taken off the rim. This issue is 
discussed above in the section on the advantages of indirect TPMSs. The 
agency notes, however, that it has not received any information 
indicating that direct TPMSs have sustained damage during driving or 
tire maintenance. The agency requests comments on the likelihood of 
such damage.
    Third, most direct TPMSs need an independent power source. Those 
that do are powered by batteries, which generally have a life span of 
five to ten years. This also means that unless a direct TPMS is 
equipped with a low battery warning indicator, the driver might not 
know when the batteries for a direct TPMS have expired.
    Finally, most direct TPMSs must be reset after a vehicle's tires 
are replaced. When a vehicle's tires are rotated, most direct TPMSs 
require that the sensor locations be reassigned in the receiver.
3. Tabular Summary of Advantages and Disadvantages of Indirect and 
Direct TPMSs

        Advantages and Disadvantages of Indirect and Direct TPMSs
------------------------------------------------------------------------
                                 Indirect TPMSs         Direct TPMSs
------------------------------------------------------------------------
Cost of adding to vehicle     $12.90..............  $79.
 with ABS, but without
 receiver.
------------------------------------------------------------------------
Cost of adding to vehicle     $12.90..............  59.
 with ABS and receiver.
------------------------------------------------------------------------
Cost of adding to vehicle     $130 for wheel speed  79.
 without ABS or receiver.      sensors; $240 for
                               ABS.
------------------------------------------------------------------------

[[Page 38989]]

 
Cost of adding to vehicle     $130 for wheel speed  59.
 without ABS, but with         sensors; $240 for
 receiver.                     ABS.
------------------------------------------------------------------------
Susceptibility of wheel       Less likely.........  More likely.
 components to damage during
 tire installation and
 removal.
------------------------------------------------------------------------
Need for an independent       No..................  Yes.
 power source.
------------------------------------------------------------------------
Need to reset after a         Yes, system must be   Yes.
 vehicle's tires are           re-calibrated.
 replaced or rotated.
------------------------------------------------------------------------
Ability to detect loss of     No..................  Yes.
 air pressure if all four
 tires lose pressure.
------------------------------------------------------------------------
Ability to detect small       No..................  Yes.
 pressure losses.
------------------------------------------------------------------------
Ability to detect under-      No, vehicle must be   Yes.
 inflated tire while vehicle   moving.
 is stationary.
------------------------------------------------------------------------
Ability to identify which     No..................  Yes.
 tire is under-inflated.
------------------------------------------------------------------------
Susceptible to giving false   Yes, if the vehicle   No.
 indications of a              is being driven on
 significantly under-          gravel or bumpy
 inflated tire.                roads or at high
                               speeds (70 mph) or if it
                               has mismatched
                               tires or a tire out
                               of balance or a out
                               of alignment.
------------------------------------------------------------------------

V. Agency Proposal

A. Summary of Proposal

    The agency is proposing two alternative versions of the TPMS 
standard. Both alternatives would require passenger cars, multipurpose 
passenger vehicles, trucks, and buses with a gross vehicle weight 
rating of 4,536 kilograms (10,000 pounds) or less, manufactured on or 
after November 1, 2003, to be equipped with a TPMS and a low tire 
pressure warning telltale (yellow) to alert the driver that one or more 
of the vehicle's tires is significantly under-inflated. Both 
alternatives would require the TPMS in each vehicle to be compatible 
with all replacement or optional tire sizes/rims recommended for that 
vehicle by the vehicle manufacturer. Both alternatives would require 
vehicle manufacturers to provide written instructions, in the owner's 
manual if one is provided, explaining the purpose of the low tire 
pressure warning telltale, the potential consequences of significantly 
under-inflated tires, and what actions drivers should take when the low 
tire pressure warning telltale is illuminated.
    The first alternative would define ``significantly under-inflated'' 
as the tire pressure 20 percent or more below the vehicle 
manufacturer's recommended cold inflation pressure for the vehicle's 
tires, or an absolute level of pressure to be specified in the new 
standard, whichever pressure is higher. It would require the low tire 
pressure warning telltale to illuminate within 10 minutes of driving 
after any tire or combination of tires on the vehicle becomes 
significantly under-inflated. It would require the low tire pressure 
warning telltale to remain illuminated as long as any of the vehicle's 
tires remains significantly under-inflated, and the ignition switch is 
in the ``on'' (``run'') position. It would require that the telltale be 
deactivatable, manually or automatically, only when the vehicle no 
longer has a tire that is significantly under-inflated.
    The second alternative would define ``significantly under-
inflated'' as the tire pressure 25 percent below the vehicle 
manufacturer's recommended cold inflation pressure for the vehicle's 
tires, or an absolute level of pressure to be specified in the new 
standard, whichever pressure is higher. The absolute pressure levels 
would be the same for both proposals. The second alternative would 
require the low tire pressure warning telltale to illuminate within 10 
minutes of driving after any tire or combination of tires, up to a 
total of three tires, becomes significantly under-inflated. Like the 
first alternative, the second alternative would require the low tire 
pressure warning telltale to remain illuminated as long as any of the 
vehicle's tires remains significantly under-inflated, and the ignition 
switch is in the ``on'' (``run'') position. The second alternative also 
would require that the telltale be deactivatable, manually or 
automatically, only when the vehicle no longer has a tire that is 
significantly under-inflated.
    The agency believes that only direct TPMSs will be able to meet the 
requirements of the first alternative. Current indirect TPMSs typically 
cannot detect significant under-inflation until the pressure in one of 
the vehicle's tires is about 30 percent below the pressure in at least 
some of the other tires. Further, they cannot detect when all four 
tires lose pressure at the same time.
    NHTSA believes that direct TPMSs and upgraded indirect TPMSs will 
be able to meet the requirements of the second alternative. The agency 
requests comments on whether this goal is practicable.

B. Vehicles Covered by This Proposal

    NHTSA is proposing to require TPMSs on passenger cars, multipurpose 
passenger vehicles, trucks, and buses with a gross vehicle weight 
rating of 4,536 kilograms (10,000 pounds) or less.
    NHTSA is not proposing to require TPMSs on motorcycles because, 
unlike the types of vehicles that would be subject to the proposed 
standard on TPMS, motorcycles use tubed tires. In order for a direct 
TPMS to work with tubed tires, the pressure sensor would not only have 
to be inside the tire, but also inside the tube itself. The agency is 
not aware of any TPMSs that are made to work with tubed tires.
    NHTSA is also not proposing to require TPMSs on medium (10,001-
26,000 lbs. GVWR) and heavy (greater than 26,001 lbs. GVWR) vehicles 
for several reasons. First, this rulemaking is required by the TREAD 
Act, which was passed in response to the Firestone recall.\13\ Since 
that recall was limited to light vehicles, the agency has limited its 
study of under-inflation to light vehicles.
---------------------------------------------------------------------------

    \13\ On August 9, 2000, Firestone announced that it was 
recalling 14.4 million ATX, ATX II, and Wilderness tires after 
receiving scores of complaints alleging that the tread on these 
tires was separating. NHTSA is investigating these tires and has 
attributed 203 deaths and more than 700 injuries to crashes 
involving tread separations on these tires.

---------------------------------------------------------------------------

[[Page 38990]]

    Second, the issues associated with under-inflated tires on medium 
and heavy vehicles are different from and more complex than the issues 
associated with under-inflated tires on light vehicles. For example, 
medium and heavy vehicles are equipped with tires that are much larger 
and have much higher pressure levels than the tires used on light 
vehicles. In addition, medium and heavy vehicles are generally equipped 
with more axles and tires than light vehicles. Since the TREAD Act 
imposed a one-year deadline on this rulemaking, the agency did not have 
the time to study and analyze those issues sufficiently.
    Third, the Federal Motor Carrier Safety Administration (FMCSA) has 
a program that is addressing tire maintenance issues on heavy, but not 
medium, vehicles. The FMCSA plans to conduct a comprehensive study, 
including possible fleet evaluations of different systems, of all the 
issues related to improvement of heavy vehicle tire maintenance.
    NHTSA plans to coordinate with the FMCSA to address the issues 
associated with heavy vehicle tire maintenance. NHTSA will work with 
the FMCSA in examining the desirability of proposing a TPMS standard 
for heavy vehicles. The agency will also consider the implications of 
those results of that examination for medium vehicles.

C. Definition of ``Significantly Under-Inflated''

    Before issuing this notice of proposed rulemaking, NHTSA employees 
attended numerous meetings with both tire and vehicle manufacturers to 
discuss TPMSs and how the term ``significantly under-inflated'' should 
be defined. The agency notes that there is a fundamental disagreement 
between vehicle and tire manufacturers as to what constitutes 
significant under-inflation.
    In general, the tire manufacturers believe that ``significantly 
under-inflated'' should be defined as any pressure below the minimum 
pressure specified by the tire industry's standard-setting bodies for a 
vehicle's gross vehicle weight rating (GVWR) or gross axle weight 
rating (GAWR). They argue that any tire with an inflation pressure 
below the pressure specified by those bodies as necessary to carry the 
vehicle's GVWR or GAWR creates a potential safety problem. They are 
concerned that tires with a pressure even 1 psi below this level will 
experience increased temperatures and be more likely to fail.
    The vehicle manufacturers would like the agency to leave the 
definition of ``significant under-inflation'' to them. They argue that 
there are too many vehicle-tire-load combinations for the agency to set 
one standard, and that the vehicle manufacturers can best determine at 
what inflation pressure a particular tire on a particular vehicle is 
significantly under-inflated. They suggest that the agency give them 
the flexibility to determine the level of significant under-inflation 
for the tires on each vehicle.
    NHTSA believes that the tire manufacturers' definition is overly 
strict. Most manufacturers of light vehicles incorporate some reserve 
when determining a tire's recommended cold inflation pressure. Thus, 
the pressure in a tire may fall below that recommended pressure without 
significantly affecting the safety of the tire.
    In addition, the pressures assigned by the tire industry's 
standard-setting bodies are simply the result of a mathematical 
calculation that a tire enclosing a given volume of air should be able 
to carry a certain load. The formula underlying the calculation is 
decades old. It remains unchanged even though tire technology and 
construction have changed significantly. A given size of today's tires 
is more able than the same size of tires 50 or even 25 years ago to 
carry a load safely. Thus, the tire industry's calculation is a very 
conservative estimate of the load-carrying capability of today's tires.
    NHTSA also does not agree with the vehicle manufacturers' 
definition. The agency believes that it must set a minimum level to 
ensure that tires are not operated at pressures the agency believes are 
too low. The agency is proposing a minimum performance standard. Either 
proposed alternative would give vehicle manufacturers the freedom to 
raise the bar. In this case, either alternative would allow them to 
design TPMSs so that they provide a warning before any tire experiences 
the amount of pressure loss permitted under the agency proposal. The 
agency also believes that a minimum performance standard specifying a 
quantified requirement can work for the various vehicle-tire-load 
combinations.
    NHTSA is proposing two alternative definitions of ``significantly 
under-inflated.'' The first would define ``significantly under-
inflated'' as a tire pressure in one, two, three or four tires that is 
20 percent or more below the vehicle manufacturer's recommended cold 
inflation pressure for the vehicle's tires, or a minimum level of 
pressure to be specified in the new standard, whichever pressure is 
higher. The second would define ``significantly under-inflated'' as a 
tire pressure in one, two, or three tires that is 25 percent or more 
below the vehicle manufacturer's recommended cold inflation pressure 
for the vehicle's tires, or a minimum level of pressure to be specified 
in the new standard, whichever pressure is higher.
    In selecting these figures, NHTSA considered several factors. 
First, there is no bright line at the loss of air pressure definitely 
becomes a safety issue. Second, we did not wish to select a level of 
pressure loss so low that the warning telltale illuminates so often 
that it becomes a nuisance. Drivers could end up ignoring such a 
telltale altogether. Accordingly, we did not want to select a level as 
low as 10 percent below the manufacturer's recommended pressure. Our 
assessment of current TPMSs leads us to conclude that detecting 20 
percent under-inflation is feasible for direct TPMSs, but may not be 
feasible for indirect ones. Most current indirect TPMSs are not able to 
detect differences in inflation pressure among a vehicle's tires that 
are less than 30 percent. However, we believe that indirect TPMSs can 
be improved sufficiently to enable them to detect 25 percent 
differentials. We are asking for comments on these figures. To aid the 
agency in selecting a figure for the final rule, NHTSA requests any 
data or analysis relating to the safety implications of under-inflation 
within the range of under-inflation discussed in this paragraph. It 
also requests information regarding the practicability of designing and 
manufacturing such systems.
    The agency has data indicating that, as the amount of under-
inflation increases, so does the negative effect on the vehicle's 
braking performance, fuel economy, and tire life. For example, 
according to data from Goodyear, a vehicle traveling at 62 mph on a wet 
surface (0.05 inch of water on the road) takes about 442 feet to stop 
if all of its tires are properly inflated. If all of its tires are 
under-inflated by 20 percent, the vehicle takes about 462 feet to stop. 
If all of its tires are under-inflated by 25 percent, the vehicle takes 
almost 470 feet to stop. The effects of 20 percent and 25 percent 
under-inflation on a vehicle's fuel economy and tire life are detailed 
in the Benefits section below.
    The agency notes that, in some cases, sole reliance on the 20 
percent or 25 percent figure would yield inflation pressures below 140 
kPa (20 psi), a pressure at which the agency believes safety may become 
an issue. For example, the lowest vehicle manufacturer's recommended 
cold inflation pressure known to the agency is 26 psi. Under the second 
alternative,

[[Page 38991]]

the low tire pressure warning telltale would not have to illuminate 
until one, two or three tires reaches 19.5 psi because 25 percent below 
26 psi is 19.5 psi.
    To prevent that from occurring, the agency is proposing to 
establish a floor. Both the 20 percent figure and the 25 percent figure 
are coupled with absolute minimum inflation pressures for the different 
types of tires. The warning telltale would have to be illuminated when 
the pressure falls to either 20 percent (first alternative) or 25 
percent (second alternative) below the vehicle manufacturer's 
recommended cold inflation pressure, or the specified absolute minimum 
inflation pressure, whichever pressure is higher. These absolute 
minimum inflation pressures are specified in the 3rd column of Table 1 
(below). (Note: The practical consequences of this floor under the 
second alternative is that manufacturers may not be able to use 
indirect TPMSs on vehicles for which the manufacturer's recommended 
pressure is 27 psi or less. This is because those systems may not be 
able to detect pressure differentials of less than 25 percent.)
    Most passenger cars, minivans and SUVs are equipped with Standard 
Load P-metric tires. NHTSA chose 140 kPa (20 psi) as the minimum 
inflation pressure for such tires based on recent testing the agency 
conducted. The agency ran a variety of Standard Load P-metric tires at 
20 psi with a load for 90 minutes on a dynamometer. None of these tires 
failed. This leads the agency to believe that warnings provided above 
that level will allow consumers to re-inflate their tires before the 
tire fails.
    140 kPa is about 58 percent of the maximum inflation pressure for 
Standard Load P-metric tires of 240 kPa. The agency calculated the 
minimum inflation pressures for the other listed tire types by 
multiplying their maximum inflation pressures by 58 percent.
    The proposed absolute minimum pressure levels for each type of tire 
are set forth in the following table:

                    Table 1.--Low Tire Pressure Warning Telltale--Minimum Activation Pressure
----------------------------------------------------------------------------------------------------------------
                                                  Maximum inflation pressure               Minimum activation
                                       ------------------------------------------------         pressure
               Tire type                                                               -------------------------
                                                 (kPa)                   (psi)             (kPa)        (psi)
----------------------------------------------------------------------------------------------------------------
P-metric--Standard Load...............  240,..................  35,...................          140           20
                                        300, or...............  44, or................          140           20
                                        350...................  51....................          140           20
----------------------------------------------------------------------------------------------------------------
P-metric--Extra Load..................  280 or................  41 or.................          160           23
                                        340...................  49....................          160           23
----------------------------------------------------------------------------------------------------------------
Load Range C..........................  350...................  51....................          200           29
----------------------------------------------------------------------------------------------------------------
Load Range D..........................  450...................  65....................          260           38
----------------------------------------------------------------------------------------------------------------
Load Range E..........................  600...................  87....................          350           51
----------------------------------------------------------------------------------------------------------------

D. Low Tire Pressure Warning Telltale

1. Color
    NHTSA is proposing to amend Standard No. 101, Controls and 
Displays, 49 CFR Sec. 571.101, to require that the warning telltale be 
yellow. The agency believes that yellow is appropriate because it 
conveys the message that the driver can continue driving, but should 
have the tire pressure checked at the earliest opportunity. Red 
represents a high level of urgency. It is used for a warning that a 
vehicle system needs immediate attention, and that it is unsafe to 
drive the vehicle farther. The agency believes that a driver needs to 
attend to a significantly under-inflated tire, but does not need to 
stop driving immediately.
2. Symbol
    NHTSA is proposing that the warning telltale be identified by one 
of the symbols shown below. The first symbol was developed by the 
International Organization for Standardization (ISO), and is currently 
used in some TPMSs. However, during its May 2001 evaluation of existing 
TPMSs, NHTSA received some negative comments from evaluators regarding 
the recognizability of this symbol.\14\ As a result, the agency 
conducted comprehension tests to determine which symbol best conveyed a 
tire pressure problem to drivers. The agency asked 120 people to look 
at a picture of 15 symbols, including the ISO symbol, and fill in the 
blank in the following statement: ``This image has just appeared on 
your vehicle's dashboard. It is a warning for ______.''
---------------------------------------------------------------------------

    \14\ An Evaluation of Existing Tire Pressure Monitoring Systems, 
May 2001. A copy of this report is available in the docket.
---------------------------------------------------------------------------

    Results of this test showed that the ISO symbol was the least 
understood among the 15 symbols, with a comprehension rate of only 38%. 
However, the agency is proposing it as a possible choice because that 
symbol is currently used in most vehicles equipped with a TPMS. Several 
of the alternative symbols were recognized 100% of the time. The second 
proposed symbol below is one of those. Based on comments on this NPRM, 
the agency will select one of those two symbols and require its use 
with the telltale.
    The third is a symbol that must be used if a vehicle manufacturer 
provides a display that identifies which tire is significantly under-
inflated. The agency notes that many vehicles already have an image of 
the vehicle built into the dashboard, with lamps located around the 
image that illuminate when there is a problem (e.g., an incompletely 
closed door) in that area. Thus, the agency is proposing this symbol in 
addition to the first two symbols.
    The three proposed symbols are below:

BILLING CODE 4910-59-P

[[Page 38992]]

[GRAPHIC] [TIFF OMITTED] TP26JY01.000

BILLING CODE 4910-59-C

[[Page 38993]]

3. Time Frame for Telltale Illumination
    As noted above, according to data from the tire industry and 
consumer surveys, 85 percent of tire pressure losses are slow pressure 
losses. These are losses in which it takes anywhere from several 
minutes to several weeks for the tire to become significantly under-
inflated. The other 15 percent of tire pressure losses are rapid 
pressure losses. These losses typically result from a tire's being 
punctured (without the puncturing object's becoming embedded in the 
tire) or ruptured. TPMSs are designed to alert the driver to slow 
pressure losses. They are not intended to alert the driver to a rapid 
pressure loss.
    The agency has received data from TPMS manufacturers indicating 
that direct TPMSs can alert the driver in less than one minute after a 
tire becomes significantly under-inflated, while indirect TPMSs can 
take up to ten minutes to do so. Since TPMSs are designed to alert the 
driver to slow pressure losses only, the agency believes that ten 
minutes is ample time. The agency believes that a TPMS that alerts the 
driver within ten minutes after a tire reaches the significant under-
inflation threshold pressure would provide the driver sufficient time 
to take corrective action and avoid serious tire degradation. Thus, the 
agency is proposing that the warning telltale must become illuminated 
not more than ten minutes after a tire becomes significantly under-
inflated.
4. Duration of Warning
    NHTSA believes that the TPMS warning telltale should be illuminated 
as long as any of the vehicle's tires remains significantly under-
inflated. The agency believes that a driver is more likely to take 
corrective action if the warning provided is continuous. Thus, in both 
alternatives, the agency is proposing that the warning telltale remain 
illuminated as long as any of the vehicle's tires remains significantly 
under-inflated, and the ignition switch is in the ``on'' (``run'') 
position, whether or not the engine is running.
    The agency would like to receive comments specifically addressing 
this proposed requirement. Would both direct and indirect TPMSs be able 
to meet this?
5. Self-Check
    During vehicle start-up, many vehicle systems provide a system 
readiness self-check or a bulb-check to provide an initial indication 
to the driver that the system is operational. NHTSA is aware that it is 
necessary to drive vehicles with indirect TPMSs for some distance so 
that the system can calibrate. As a result, these systems may not be 
capable of completing a full system self-check before the vehicle is 
driven. The agency also has no data indicating how often bulbs burn 
out. As a result, the agency is not proposing a system self-check or a 
bulb-check requirement. The agency requests comments on whether the 
standard should require a complete system check, a bulb-check, or no 
check.

E. System Calibration and Reset

    NHTSA notes that most indirect TPMSs need substantial time to 
calibrate the system, i.e., to ``learn'' the variables associated with 
distinct tire types under varying driving conditions. The VRTC found 
that the four indirect TPMSs it evaluated took anywhere from several 
minutes to several hours to calibrate. This calibration is necessary 
when a vehicle is first driven, when the pressure in a tire is changed, 
and when the tires are rotated or replaced.
    Indirect TPMSs do not indicate that the system is in calibration 
mode. During the calibration mode, the system is not monitoring tire 
pressure. Thus, if one or more tires becomes significantly under-
inflated while the system is calibrating, the driver would not be 
alerted.
    The agency is not proposing in either alternative that the TPMS 
indicate to the driver that the system is in calibration mode. The 
value of such an indication would likely be negligible since the system 
would only rarely be in that mode. Recalibration by the driver would 
typically occur only after replacing, rotating or reinflating tires. 
Nevertheless, the agency requests comment on this. Should this 
requirement be included?
    NHTSA also notes that some TPMSs automatically extinguish the 
warning telltale when the inflation pressure in a tire rises above the 
threshold level for warning indication. These systems thus require no 
action on the part of the driver.
    Other TPMSs make it necessary for the driver to reset the system by 
means of a reset button after taking action to resolve the low tire 
pressure problem. This may invite human error or abuse. For example, a 
driver may accidentally press the reset button when one or more of the 
vehicle's tires is under-inflated, but not under-inflated enough to 
illuminate the low tire pressure warning telltale. This would re-
calibrate the system so that the under-inflated condition would be 
accepted as a normal variable. The indirect TPMS then would not be able 
to detect a significantly under-inflated tire until one or more tires 
was 20 percent or more lower than it already was. This could also occur 
if the driver simply pressed the reset button when the low tire 
pressure warning telltale illuminated. The indirect TPMS would re-
calibrate the system so that the under-inflated condition would be 
accepted as a normal variable, and the system would not be able to 
detect a significantly under-inflated tire until it was 20 percent or 
more lower than it already was.
    The agency is proposing that the warning telltale deactivate, 
manually or automatically, only when all of the vehicle's tires cease 
to be significantly under-inflated. The agency requests comment on this 
potential problem.

F. System Failure

    NHTSA is not proposing that the TPMS must alert the driver in the 
event of a system malfunction, e.g., by adding a separate system 
failure telltale. The agency believes that such a requirement might be 
too costly. However, NHTSA solicits comments on this issue. How 
difficult would it be to add a system malfunction feature to TPMSs? 
What are the possible safety benefits of such a feature?

G. Number of Tires Monitored

    In the first alternative, the agency is proposing that the TPMS be 
able to detect when one to four tires becomes significantly under-
inflated. In the second alternative, the agency is proposing that the 
TPMS be able to detect when one to three tires becomes significantly 
under-inflated. The reason for this difference is that direct TPMSs can 
detect when all four tires become significantly under-inflated, but 
most indirect TPMSs cannot.
    The agency is requesting comments on whether the second alternative 
should require that the TPMS be able to detect when all four tires 
become significantly under-inflated. Under both alternatives, indirect 
TPMSs would require some improvements in their performance. Current 
indirect TPMSs that can detect under-inflation only when a tire is 30 
percent or more below would have to be improved so they could meet the 
25 percent under-inflation requirement for one to three tires. Would 
requiring that indirect TPMSs be able to detect when all four tires 
become significantly under-inflated be a reasonable goal? What would 
the additional benefits and costs of such a requirement be?

H. Replacement Tires/Rims

    NHTSA believes that it is important that a TPMS be able to function

[[Page 38994]]

properly when the vehicle's original tires are replaced. Thus, the 
agency is proposing to require that each TPMS be able to meet the 
requirements of the new standard when any of the vehicle's original 
tires or rims are replaced with any optional or replacement tire/rim 
size(s) recommended for use on the vehicle by the vehicle manufacturer.

I. Monitoring of Spare Tire

    The Federal motor vehicle safety standards do not require vehicles 
to be equipped with a spare tire. Thus, the agency is not proposing 
that the TPMS monitor the pressure in the spare tire while it is 
stowed.

J. Written Instructions

    NHTSA is proposing that the vehicle's owner's manual provide an 
image of the TPMS symbol with the following information, in English: 
``When the TPMS warning light is lit, one of your tires is 
significantly under-inflated. You should stop and check your tires as 
soon as possible, and inflate them to the proper pressure as indicated 
on the vehicle's tire inflation placard. Driving on an under-inflated 
tire causes the tire to overheat and can eventually lead to tire 
failure. Under-inflation also reduces fuel efficiency and tire tread 
life, and may affect the vehicle's handling and stopping ability.'' 
Each vehicle manufacturer may, at its discretion, provide additional 
information about the significance of the low tire pressure warning 
telltale illuminating and description of corrective action to be 
undertaken.
    The agency believes that drivers would need this information so 
that they would know what to do if the low tire pressure warning 
telltale illuminates. The agency also believes that more drivers will 
inflate their tires, and thus experience the benefits associated with 
properly inflated tires, if they understand the potential consequences 
of significantly under-inflated tires. The agency requests comments 
addressing this issue. Is this information sufficient, or should the 
agency require additional information in the owner's manual?

K. Temperature Compensation

    During the driving of a motor vehicle, the temperature in its tires 
increases. The increased temperature causes increases in the inflation 
pressure in the tire.\15\ This phenomenon could impact the ability of a 
TPMS to measure or calculate the actual pressure in a tire accurately. 
A temperature compensation feature in a TPMS compensates for the 
increased inflation due to temperature increases. Some direct TPMSs 
employ pressure and temperature sensors located in the wheel. The 
agency is aware of no indirect TPMSs that are capable of compensating 
for temperature increases in tires.
---------------------------------------------------------------------------

    \15\ The actual tire pressure increase due to heat appears to 
depend on several factors, including whether the tire is under-
inflated to start with, the load on the tire, and how much braking 
has occurred recently. The agency believes that the maximum increase 
in tire pressure due to increased temperature is 4 psi.
---------------------------------------------------------------------------

    It is possible that, without temperature compensation, the 
illumination of the low tire pressure warning telltale could be delayed 
due to the increased pressure caused by increased temperature. The 
telltale also could be extinguished due to the increased tire pressure 
experienced during normal operation. In addition, large fluctuations in 
the ambient temperature could result in the low tire pressure warning 
telltale's being activated on vehicles during ignition, and then de-
activated after the vehicle has been driven for awhile and the 
temperature (and thus the pressure) in a tire increases.
    NHTSA is not proposing to require a temperature compensation 
feature in either proposed alternative. The agency believes such a 
requirement would have limited value and add slightly to the cost of 
the proposed standard. The agency also believes that indirect TPMSs 
would not be able to meet such a requirement. However, the agency is 
concerned that TPMSs without a temperature compensation feature could 
allow the cold tire pressure to fall below the absolute minimum 
inflation pressure proposed in Table 1 without warning the driver. The 
agency requests comments on whether the standard should include a 
temperature compensation requirement, and what the safety benefits and 
costs of such a requirement would be. Also, if NHTSA did require a 
temperature compensation feature, how would the agency test/regulate 
it?
    Alternatively, the agency could amend the test procedures to 
specify a cool-down period for tires after a vehicle's TPMS has been 
tested. This may make the tests more repeatable and accurate. The 
agency requests comments on this issue.

L. Test Conditions

    Under both alternatives, NHTSA is proposing that each vehicle be 
tested at its gross vehicle weight rating (GVWR) and its lightly loaded 
vehicle weight (LLVW), defined as unloaded vehicle weight plus up to 
400 pounds (including test driver and instrumentation). The ambient 
temperature would be between 0 deg.C (32 deg.F) and 40 deg.C 
(104 deg.F). The test road surface would be dry and smooth. The vehicle 
would be tested at a speed between 50 km/h (31.1 mph) and 100 km/h 
(62.2 mph).
    The agency requests comments on these test conditions. For example, 
some indirect TPMSs require the vehicle to be driven at a variety of 
speeds, including stops and starts, to calibrate. The agency is 
proposing that vehicles be tested at a speed between 50 km/h and 100 
km/h. This would exclude the stops and starts necessary for some 
indirect TPMSs to calibrate. It also would necessitate the use of 
nonpublic test courses, as opposed to public roads, for testing 
purposes. At what speeds should vehicles be tested? Are there any other 
driving conditions under which vehicles should be tested?

M. Test Procedures

    In both alternatives, NHTSA is proposing that the vehicle's tires 
be inflated to the vehicle manufacturer's recommended cold inflation 
pressure. Then the vehicle would be driven between 50 km/h and 100 km/h 
for up to 20 minutes.
    Under the first alternative, while driving at that speed, any 
combination of tires (from one to all four) is deflated until it is 
significantly under-inflated. Then the elapsed time between the time 
the vehicle's tire or combination of tires becomes significantly under-
inflated and the time the low tire pressure warning telltale is 
illuminated is recorded. After the warning telltale illuminates, 
pressure is added to the tire or combination of tires that was deflated 
such that the tire or each of those tires is one psi below the level of 
significant under-inflation. Then the warning telltale is checked to 
see if it remains illuminated. If the warning telltale remains 
illuminated, a manual reset is attempted.
    Under the second alternative, the procedures are the same, except 
any combination of tires (from one to three) is deflated until it is 
significantly under-inflated.
    Under both alternatives, the agency is proposing that the test 
procedures be repeated for each tire and rim combination recommended by 
the vehicle manufacture for that vehicle. The agency requests comments 
on whether there are any steps that should be taken between testing 
different tire and rim combinations and that should be added to the 
test procedures.
    The agency requests comment on all aspects of these test 
procedures. Should

[[Page 38995]]

the agency specify more or less than 20 minutes for the system to 
calibrate? As noted above in the section on Temperature Compensation, 
the inflation pressure in tires increases as they heat up during normal 
operation. This may cause variations in testing. To ensure 
repeatability, should the agency specify that tires be tested cold? Are 
there any other procedures the agency should specify?

N. Human Factors

    There are two human factors issues involved with TPMSs. The first 
is what information is displayed to the driver and how that information 
is displayed. The second is whether the driver responds to the 
information by checking and inflating the vehicle's tires.
    Regarding the information displayed to the driver, NHTSA is 
proposing only a warning telltale that would illuminate when one or 
more of the vehicle's tires becomes significantly under-inflated. The 
agency is not proposing that the pressure in each tire be displayed. 
However, in NHTSA's analysis of the benefits, both in the PEA and 
below, the agency assumes that manufacturers who install direct TPMSs 
will display the pressure in each tire because it will be helpful to 
drivers in terms of safety, fuel economy, and tread life. Most indirect 
TPMSs are not capable of displaying the pressure in each tire.
    The agency anticipates that drivers would react differently to the 
different information they receive from TPMSs. Some drivers of vehicles 
equipped with a direct TPMS would keep track of the pressure in each 
tire and add pressure to their tires whenever necessary, even before 
the warning telltale becomes illuminated. These drivers would accrue 
more benefits in terms of increased safety, fuel efficiency, and tread 
life than drivers who wait until the warning telltale becomes 
illuminated.
    On the other hand, some drivers who currently check and inflate 
their own tires frequently enough to avoid significant under-inflation 
may start to rely on the TPMS warning telltale to indicate under-
inflation. The agency believes that this would happen more often with 
drivers of vehicles equipped with an indirect TPMS, which only 
illuminate a warning telltale when one or more tires becomes 
significantly under-inflated, than with drivers of vehicles equipped 
with a direct TPMS, which display the pressure in each tire. These 
drivers would accrue fewer benefits in terms of safety, fuel 
efficiency, and tread life.
    NHTSA does not have any information on which to base an estimate of 
the percentage of drivers who would use the information from a display 
of the pressure in each tire to inflate their tires more frequently 
than they currently do, or the percentage of drivers who would rely on 
the TPMS warning telltale to indicate under-inflation and inflate their 
tires less frequently than they currently do. The agency requests 
comment on this issue.

VI. Benefits

    Following is a summary of the benefits associated with the two 
proposed alternatives. For a more detailed analysis, see the agency's 
Preliminary Economic Assessment (PEA). A copy of the PEA has been 
placed in the docket.
    For purposes of this analysis, the agency assumed that vehicles 
with a direct TPMS will display a continuous readout of the pressure in 
each tire and have a warning telltale that illuminates when the 
vehicle's tires become significantly under-inflated. The agency assumed 
that 80 percent of drivers would react to this tire-specific 
information and re-inflate the significantly under-inflated tire(s). 
For indirect TPMSs, the agency assumed that only 60 percent of drivers 
would react to a low tire pressure warning telltale and re-inflate 
their significantly under-inflated tire(s). The agency requests 
comments on these assumptions.
    The safety benefits that the agency has quantified come from 
calculations of a reduction in stopping distance for vehicles with 
properly inflated tires. NHTSA notes that the relationship of tire 
inflation to stopping distance is influenced by road conditions (i.e., 
wet versus dry), as well as by the road surface composition.
    In tests conducted by Goodyear, significant increases were found in 
the stopping distance of tires that were under-inflated. By contrast, 
tests conducted by NHTSA at the VRTC testing ground found only minor 
differences in stopping distance. In some cases, these distances 
actually decreased with lower inflation pressure. The VRTC tests also 
found only minor differences between wet and dry road surface stopping 
distance.
    It is likely that some of these differences are due to test track 
surface characteristics. The VRTC track surface is considered to be 
extremely aggressive in that it allows for maximum friction with tire 
surfaces. It is more representative of a new road surface than the worn 
surfaces on the vast majority of roads.
    The Goodyear tests may be biased in other ways. Their basic wet 
surface tests were conducted on surfaces with .05 inch of standing 
water. This more than typically would be encountered under normal wet 
road driving conditions, and thus may exaggerate the stopping distances 
experienced under most circumstances. On the other hand, crashes are 
more likely to occur under more hazardous conditions, which may mean 
that the Goodyear data are less biased when applied to the actual 
crash-involved population.
    Generally speaking, the Goodyear test results imply a significant 
impact on stopping distance from properly inflated tires, while the 
VRTC test results imply these impacts would be minor or nonexistent. 
The analysis below and in the PEA estimates stopping distance impacts 
using the Goodyear data to establish an upper range of potential 
benefits. A lower range of no benefit is implied by the current VRTC 
test results. The estimates detailed below are the mid-points between 
the upper and lower range of potential benefits.
    The benefits from preventable crashes were assumed to occur over 
all crash types and severities. This assumption recognizes that there 
are a variety of crash circumstances for which marginal reductions in 
stopping distance may prevent the crash from occurring. Crash 
prevention may be more likely under some circumstances than others. For 
example, it is possible that a larger portion of side impact crashes 
than head-on crashes might be prevented. In side impact crashes where 
vehicles are moving perpendicular to each other, reduced stopping 
distance by one vehicle reduces the speed at which it enters the crash 
zone and potentially allows the second vehicle to move through the 
crash zone, thus avoiding the impact. In a head-on collision, both 
vehicles are moving toward the crash and a reduction in stopping 
distance for one vehicle may not improve the chances of avoiding the 
crash as much as in a side impact situation. Moreover, if a separate 
analysis were conducted for different crash types and severities, the 
portion of crashes prevented would be greater for crashes at higher 
speeds. However, NHTSA does not have sufficient information to conduct 
a separate analysis of each crash circumstance. Instead, the agency has 
used an overall estimate across all crash types. The agency requests 
comment on this issue.

A. First Alternative

    The first alternative would require the TPMS to illuminate the low 
tire pressure warning telltale when pressure in any tire or combination 
of tires decreases to 20 percent below the vehicle manufacturer's 
recommended

[[Page 38996]]

cold inflation pressure for the vehicle's tires or the absolute value 
specified in proposed Table 1, whichever is higher. Thus, the TPMS 
would have to provide warning when any number of tires, from one to 
four tires, is significantly under-inflated.
    When a vehicle's tires are under-inflated, and it is traveling on a 
wet surface, the vehicle takes longer to stop than when its tires are 
properly inflated. For example, according to data from Goodyear, a 
vehicle traveling at 62 mph on a wet surface takes about 442 feet to 
stop if its tires are properly inflated. If its tires are under-
inflated by 20 percent, the vehicle takes about 462 feet to stop.
    The Goodyear data indicates that, under the first alternative, the 
average stopping distance of passenger cars across all speeds and 
driving conditions would be reduced from 137 feet (the average stopping 
distance for a vehicle with tires 20 percent under-inflated) to 132.1 
feet (the average stopping distance for a vehicle with properly 
inflated tires). The average stopping distance of light trucks would be 
reduced from 131.5 feet to 127.3 feet. This would reduce the number of 
crashes involving braking passenger cars by 3.6 percent and braking 
light trucks by 3.2 percent. The other 96.4 percent of crashes 
involving braking passenger cars and 96.8 percent of crashes involving 
braking light trucks would still occur, but at a reduced impact speed. 
The agency estimates that this would result in 79 fewer fatalities and 
would prevent or reduce in severity 10,635 nonfatal injuries.\16\
---------------------------------------------------------------------------

    \16\ The range of injuries prevented would be 0 to 21,270, and 
the range of deaths prevented would be 0 to 158.
---------------------------------------------------------------------------

    Correct tire pressure also improves a vehicle's fuel economy. 
Recent data from Goodyear indicate that a vehicle's fuel efficiency is 
reduced by one percent for every 2.96 psi that its tires are below the 
vehicle manufacturer's recommended cold inflation pressure. NHTSA 
estimates that, under the first alternative, the average vehicle would 
get a little over 2 percent higher fuel economy. This translates into 
an average discounted value of $32.22 (in 2001 dollars) over the 
lifetime of the vehicle for passenger cars and light trucks.
    Correct tire pressure also increases a tire's life. Data from 
Goodyear indicate that for every 1 psi drop in tire pressure, tread 
life decreases by 1.78 percent. NHTSA estimates that under the first 
alternative, the average tire life would increase by 1,404 miles for 
passenger cars and 1,972 miles for light trucks. This would delay new 
tire purchases. The agency estimates that the average discounted value 
of these delayed tire purchases is $5.26 for passenger cars and $16.80 
for light trucks.

B. Second Alternative

    The second alternative requires the TPMS to illuminate the low tire 
pressure warning telltale when pressure in any tire or combination of 
tires, up to a total of three tires, decreases to 25 percent below the 
vehicle manufacturer's recommended cold inflation pressure for the 
vehicle's tires, or the absolute value specified in proposed Table 1, 
whichever is higher.
    NHTSA estimates that the second alternative would also reduce a 
vehicle's stopping distance. However, since the pressure level at which 
the driver is warned is lower in the second alternative (25 percent 
versus 20 percent), fewer drivers would receive a low tire pressure 
warning. Thus, fewer drivers would inflate their tires to the proper 
pressure, and fewer vehicles would experience the reduced stopping 
distance. Consequently, the agency estimates that under the second 
alternative, the reduction in stopping distance would result in 49 
fewer fatalities and would prevent or reduce in severity 6,585 nonfatal 
injuries.\17\
---------------------------------------------------------------------------

    \17\ The range of injuries prevented would be 0 to 13,170, and 
the range of deaths prevented would be 0 to 97.
---------------------------------------------------------------------------

    NHTSA estimates that under the second alternative, vehicles' fuel 
economy would be improved. However, fewer vehicles would experience 
this improvement for the reasons stated in the previous paragraph. 
Consequently, the agency estimates that under the second alternative, 
improved fuel economy would translate into an average discounted value 
of $16.40 (in 2001 dollars) over the lifetime of the vehicle for 
passenger cars and light trucks.
    NHTSA estimates that under the second alternative, tire life would 
be increased by 1,131 miles for passenger cars and 1,615 miles for 
light trucks if they are equipped with a direct TPMS. If they are 
equipped with an indirect TPMS, the agency estimates that tire life 
would be increased by 635 miles for passenger cars and 615 miles for 
light trucks. This would delay new tire purchases. The agency estimates 
that the average discounted value of these delayed tire purchases is 
$4.24 for passenger cars and $13.84 for light trucks if they are 
equipped with a direct TPMS, and $2.39 for passenger cars and $5.17 for 
light trucks if they are equipped with an indirect TPMS.
    NHTSA notes that longer tire life is an economic benefit rather 
than a safety benefit. The agency is concerned that tires' tread may 
last longer than other parts of the tire, e.g., the sidewall. Most 
drivers change their tires when the tread is low. If the tread outlasts 
the rest of the tire, the tire may fail. The agency believes that part 
of the cause of the Firestone problem was that the tread lasted longer 
than expected, allowing other failures to occur. The agency requests 
comment on this issue.

C. Unquantified Benefits

    The agency believes the proposals would also result in other 
benefits, such as fewer crashes resulting from tire blowouts, adverse 
effects on vehicle handling due to inflation pressure loss and 
hydroplaning, from fewer crashes involving vehicles that had been 
stopped by the side of the road because of a flat tire, and the 
prevention of the property damage that results from these crashes. For 
more information on these unquantified benefits, see the PEA. NHTSA has 
not attempted to quantify those benefits. The agency requests comment 
on these unquantified benefits.

VII. Costs

A. Indirect TPMSs

    The costs of incorporating an indirect TPMS into a vehicle would 
vary depending on the way in which the incorporation is accomplished. 
In order to add a current ABS-based indirect TPMS to a motor vehicle 
that already has an ABS, the agency assumes that the vehicle's 
manufacturer would only have to add the capability to monitor the wheel 
speed sensors, a low tire pressure warning telltale, and a reset 
button, and make some software changes. NHTSA estimates that the cost 
of adding these features would be about $12.90 per vehicle. However, as 
explained below, the agency is uncertain whether the resulting ABS-
based indirect TPMS would comply with either alternative.
    NHTSA tested four current ABS-based indirect TPMSs. None of the 
four met the proposed requirements for either alternative. These TPMSs 
had problems detecting two significantly under-inflated tires on the 
same axle and on the same side of the vehicle. They also did not 
illuminate the low tire pressure warning telltale when the pressure in 
the vehicle's tires decreased to 20 percent, or even 25 percent, below 
the vehicle manufacturer's recommended cold inflation pressure. NHTSA 
does not know whether improving current indirect TPMSs to meet the 
requirements of either alternative would

[[Page 38997]]

result in additional costs. The agency requests comments on this issue.
    Pickup trucks comprise about 40 percent of light truck sales. Some 
percentage of pickup trucks that have ABS have only one wheel speed 
sensor for the rear axle. In order to meet the requirements of either 
proposed alternative, NHTSA believes vehicle manufacturers would have 
to add a fourth wheel speed sensor to these trucks at an estimated cost 
of $20 per vehicle. The agency assumes for this analysis that about 10 
percent of all light trucks, or 7.5 percent of all light vehicles with 
ABS, would be in this category. However, the agency requests comment on 
the percentage of pickup trucks that would require this modification.
    For vehicles currently without ABS, there are two indirect 
measurement choices. First, the vehicle manufacturer could add ABS and 
the necessary TPMS features to the vehicle. NHTSA estimates that this 
would cost about $240 per vehicle. The agency does not expect 
manufacturers that make this choice unless they are already planning 
for other reasons to add ABS. Second, the vehicle manufacturer could 
add wheel speed sensors and the necessary TPMS features to the vehicle. 
NHTSA estimates that this approach would cost about $130 per vehicle.

B. Direct TPMSs

    There are two main costs associated with direct TPMSs: sensors and 
a receiver. There is a wide disparity in costs for sensors, depending 
on what type of information is sensed. Providing pressure sensors would 
cost from $5 to $10 per wheel, or $20 to $40 per vehicle.
    The cost of the receiver depends upon whether the vehicle already 
has a receiver capable of receiving and processing the information 
coming from the sensors. NHTSA estimates that about 60 percent of 
vehicles currently have such a receiver. Making some software changes 
and adding a display showing the pressure for each tire would cost 
about $25 per vehicle. The 40 percent of vehicles without such a 
receiver would have to be equipped with a receiver, a display, and the 
necessary software. The agency estimates that this would cost about $40 
to $50 per vehicle.
    The agency estimates that installation costs for a direct TPMS 
would be about $4 per vehicle.
    Thus, the agency estimates that the cost of adding a direct TPMS to 
a vehicle that is already equipped with a receiver would be $49 to $69. 
For a vehicle that is not already equipped with a receiver, the cost 
would be $64 to $94. The agency used the midpoints of $59 and $79 to 
determine the cost per vehicle of the first alternative
    NHTSA determined the current use of TPMSs in new vehicles by using 
the calendar year 2000 sales, a model year 2001 list of the makes and 
models with each type of system, and an estimate that 2 percent of 
sales were purchased as an option on those models that offered a TPMS 
as an option. As a result, the agency estimates that 4 percent of the 
model year 2001 light vehicle fleet has an indirect TPMS, and 1 percent 
of the fleet has a direct TPMS.
    NHTSA conducted tear down studies of two currently available direct 
TPMSs, one produced by Beru and the other produced by Johnson Controls. 
The agency chose the Beru TPMS because it is considered top-of-the-
line. It also was the most expensive direct TPMS the agency found on 
the market, at a cost of $200. The Johnson Controls direct TPMS, on the 
other hand, is typical of most direct TPMSs. It cost only $69, similar 
to the costs estimated by the agency.

C. Testing and Maintenance Costs

    There are some costs that would be associated with both direct and 
indirect TPMSs. For example, both systems would have to be tested for 
compliance with the proposed requirements. The agency estimates that 
the man-hours required to complete the testing would be 6 hours for a 
manager, 30 hours for a test engineer, and 30 hours for a test 
technician/driver. The agency estimates labor costs would be $75 per 
hour for a manager, $53 per hour for a test engineer, and $31 per hour 
for a test technician/driver. Thus, the agency estimates total testing 
costs would be $2,970 per vehicle model.

D. Unquantified Costs

    The agency believes the proposals may also result in additional 
costs, such as the cost of replacing worn or damaged TPMS equipment, 
the cost of replacing batteries in a direct TPMS, and the cost of the 
time it would take for a driver to react to a low tire pressure warning 
by pulling over to a gas station to check and inflate the vehicle's 
tires. NHTSA has not attempted to quantify those costs. The agency 
requests comment on these unquantified costs.

E. First Alternative

    Assuming that installation of a direct TPMS would be necessary to 
achieve compliance, the agency estimates that the average incremental 
cost would be $66.33 per vehicle. This would result in an average net 
cost of $23.08 per vehicle ($66.33-$32.22 (fuel savings)-$11.03 (tread 
wear savings)), and a net cost per equivalent life saved of $1.9 
million. The total annual cost would be about $1.06 billion, or $369 
million when the fuel and tread wear savings are factored in.

F. Second Alternative

    An indirect TPMS for all passenger cars and light trucks that are 
already equipped with an ABS would cost an average of $12.90 per ABS-
equipped vehicle. The agency assumes that vehicle manufacturers would 
choose to equip vehicles that are not equipped with an ABS with a 
direct TPMS because it is cheaper than adding wheel speed sensors or an 
ABS. The average cost of adding a direct TPMS would be $66.33 per 
vehicle. The agency estimates that the overall cost of the second 
alternative would be $30.54 per vehicle, since 67 percent of vehicles 
are equipped with an ABS, while 33 percent are not. This would result 
in an average net cost of $8.63 ($30.54-$16.40 (fuel savings)-$5.51 
(tread wear savings)) per vehicle, and a net cost per equivalent life 
saved of $1.1 million. The total annual cost would be about $489 
million, or $138 million when the fuel and tread wear savings are 
factored in.

VIII. Lead-Time

    The TREAD Act requires that this rule take effect two years after 
the final rule is issued. Since the final rule must be issued by 
November 1, 2001, the rule must take effect not later than November 1, 
2003.
    NHTSA requests comment on whether vehicle manufacturers will be 
able to meet the statutory deadline, and whether TPMS manufacturers 
will be able to supply enough TPMSs to meet the demand under either of 
the alternatives proposed in this NPRM.
    The agency requests comments also on whether a phase-in beginning 
on November 1, 2003, would be appropriate. Such a phase-in might 
provide for the compliance of 35 percent of production in the first 
year (2003), 65 percent in the second year (2004), and 100 percent in 
the third year (2005). If a phase-in were adopted, should carry forward 
credit be given for early compliance?

IX. Rulemaking Analyses and Notices

A. Executive Order 12866 and DOT Regulatory Policies and Procedures

    Executive Order 12866, ``Regulatory Planning and Review'' (58 FR 
51735, October 4, 1993), provides for making

[[Page 38998]]

determinations whether a regulatory action is ``significant'' and 
therefore subject to Office of Management and Budget (OMB) review and 
to the requirements of the Executive Order. The Order defines a 
``significant regulatory action'' as one that is likely to result in a 
rule that may:
    (1) Have an annual effect on the economy of $100 million or more or 
adversely affect in a material way the economy, a sector of the 
economy, productivity, competition, jobs, the environment, public 
health or safety, or State, local, or Tribal governments or 
communities;
    (2) Create a serious inconsistency or otherwise interfere with an 
action taken or planned by another agency;
    (3) Materially alter the budgetary impact of entitlements, grants, 
user fees, or loan programs or the rights and obligations of recipients 
thereof; or
    (4) Raise novel legal or policy issues arising out of legal 
mandates, the President's priorities, or the principles set forth in 
the Executive Order.
    This proposal is economically significant. Accordingly, it was 
reviewed under Executive Order 12866. The rule is also significant 
within the meaning of the Department of Transportation's Regulatory 
Policies and Procedures. The agency has estimated that compliance with 
this proposed rule would cost from $30.54 to $66.33 per vehicle per 
year. Since approximately 16 million vehicles are produced for the 
United States market each year, this proposal would have greater than a 
$100 million effect.
    Because this proposed rule is significant, the agency has prepared 
a Preliminary Economic Analysis (PEA). This analysis is summarized 
above in the sections on Benefits and Costs. The PEA is available in 
the docket and has been placed on the agency's website along with the 
proposal itself.

B. Regulatory Flexibility Act

    Pursuant to the Regulatory Flexibility Act (5 U.S.C. 601 et seq., 
as amended by the Small Business Regulatory Enforcement Fairness Act 
(SBREFA) of 1996), whenever an agency is required to publish a notice 
of rulemaking for any proposed or final rule, it must prepare and make 
available for public comment a regulatory flexibility analysis that 
describes the effect of the rule on small entities (i.e., small 
businesses, small organizations, and small governmental jurisdictions). 
The Small Business Administration's regulations at 13 CFR part 121 
define a small business, in part, as a business entity ``which operates 
primarily within the United States.'' (13 CFR 121.105(a)). No 
regulatory flexibility analysis is required if the head of an agency 
certifies the rule will not have a significant economic impact on a 
substantial number of small entities. SBREFA amended the Regulatory 
Flexibility Act to require Federal agencies to provide a statement of 
the factual basis for certifying that a rule will not have a 
significant economic impact on a substantial number of small entities.
    NHTSA has considered the effects of this proposed rule under the 
Regulatory Flexibility Act. I certify that this proposed rule would not 
have a significant economic impact on a substantial number of small 
entities. The rationale for this certification is that currently there 
are only four small motor vehicle manufacturers in the United States 
that would have to comply with this proposed rule. These manufacturers 
would have to rely on suppliers to provide the TPMS hardware, and then 
they would have to integrate the TPMS into their vehicles.
    There are a few small manufacturers that manufacture recreational 
vehicles which would have to comply with this proposed rule. However, 
most of these manufacturers use van chassis supplied by the larger 
manufacturers, e.g., General Motors, Ford, or DaimlerChrysler, and 
could use the TPMSs supplied with the chassis. These manufacturers also 
would not have to test the TPMS for compliance with this proposed rule 
since they would be able to rely upon the chassis manufacturer's 
incomplete vehicle documentation.

C. National Environmental Policy Act

    NHTSA has analyzed this rulemaking action for the purposes of the 
National Environmental Policy Act. The agency has determined that 
implementation of this proposed rule would not have any significant 
impact on the quality of the human environment.

D. Executive Order 13132 (Federalism)

    Executive Order 13132 requires NHTSA to develop an accountable 
process to ensure ``meaningful and timely input by State and local 
officials in the development of regulatory policies that have 
federalism implications.'' ``Policies that have federalism 
implications'' is defined in the Executive Order to include regulations 
that have ``substantial direct effects on the States, on the 
relationship between the national government and the States, or on the 
distribution of power and responsibilities among the various levels of 
government.'' Under Executive Order 13132, the agency may not issue a 
regulation with Federalism implications, that imposes substantial 
direct compliance costs, and that is not required by statute, unless 
the Federal government provides the funds necessary to pay the direct 
compliance costs incurred by State and local governments, the agency 
consults with State and local governments, or the agency consults with 
State and local officials early in the process of developing the 
proposed regulation. NHTSA also may not issue a regulation with 
Federalism implications and that preempts State law unless the agency 
consults with State and local officials early in the process of 
developing the proposed regulation.
    The agency has analyzed this proposed rule in accordance with the 
principles and criteria set forth in Executive Order 13132 and has 
determined that it would not have sufficient federalism implications to 
warrant consultation with State and local officials or the preparation 
of a federalism summary impact statement. The proposal would not have 
any substantial effects on the States, or on the current Federal-State 
relationship, or on the current distribution of power and 
responsibilities among the various local officials.

E. Civil Justice Reform

    This proposed amendment would not have any retroactive effect. 
Under 49 U.S.C. 30103, whenever a Federal motor vehicle safety standard 
is in effect, a State may not adopt or maintain a safety standard 
applicable to the same aspect of performance which is not identical to 
the Federal standard, except to the extent that the state requirement 
imposes a higher level of performance and applies only to vehicles 
procured for the State's use. 49 U.S.C. 30161 sets forth a procedure 
for judicial review of final rules establishing, amending, or revoking 
Federal motor vehicle safety standards. That section does not require 
submission of a petition for reconsideration or other administrative 
proceedings before parties may file suit in court.

F. Paperwork Reduction Act

    Under the Paperwork Reduction Act of 1995, a person is not required 
to respond to a collection of information by a Federal agency unless 
the collection displays a valid OMB control number. This proposed rule 
would not require any collections of information as defined by the OMB 
in 5 CFR Part 1320.

G. National Technology Transfer and Advancement Act

    Section 12(d) of the National Technology Transfer and Advancement

[[Page 38999]]

Act of 1995 (NTTAA), Public Law 104-113, section 12(d) (15 U.S.C. 272) 
directs us to use voluntary consensus standards in our regulatory 
activities unless doing so would be inconsistent with applicable law or 
otherwise impractical. Voluntary consensus standards are technical 
standards (e.g., materials specifications, test methods, sampling 
procedures, and business practices) that are developed or adopted by 
voluntary consensus standards bodies, such as the Society of Automotive 
Engineers (SAE). The NTTAA directs us to provide Congress, through OMB, 
explanations when we decide not to use available and applicable 
voluntary consensus standards.
    There are no voluntary consensus standards available at this time. 
However, NHTSA will consider any such standards when they become 
available.

H. Unfunded Mandates Reform Act

    Section 202 of the Unfunded Mandates Reform Act of 1995 (UMRA) 
requires Federal agencies to prepare a written assessment of the costs, 
benefits, and other effects of proposed or final rules that include a 
Federal mandate likely to result in the expenditure by State, local or 
tribal governments, in the aggregate, or by the private sector, of more 
than $100 million in any one year (adjusted for inflation with base 
year of 1995). Before promulgating a rule for which a written statement 
is needed, section 205 of the UMRA generally requires NHTSA to identify 
and consider a reasonable number of regulatory alternatives and adopt 
the least costly, most cost-effective, or least burdensome alternative 
that achieves the objectives of the rule. The provisions of section 205 
do not apply when they are inconsistent with applicable law. Moreover, 
section 205 allows NHTSA to adopt an alternative other than the least 
costly, most cost-effective, or least burdensome alternative if the 
agency publishes with the final rule an explanation why that 
alternative was not adopted.
    This proposed rule would not result in the expenditure by State, 
local, or tribal governments, in the aggregate, of more than $100 
million annually, but it would result in the expenditure of that 
magnitude by vehicle manufacturers and/or their suppliers. This 
document seeks comments on two alternatives for achieving the purposes 
of the TREAD Act mandate.

I. Plain Language

    Executive Order 12866 requires each agency to write all rules in 
plain language. Application of the principles of plain language 
includes consideration of the following questions:

--Have we organized the material to suit the public's needs?
--Are the requirements in the rule clearly stated?
--Does the rule contain technical language or jargon that is not clear?
--Would a different format (grouping and order of sections, use of 
headings, paragraphing) make the rule easier to understand?

--Would more (but shorter) sections be better?
--Could we improve clarity by adding tables, lists, or diagrams?
--What else could we do to make this rulemaking easier to understand?
    If you have any responses to these questions, please include them 
in your comments on this NPRM.

J. Regulation Identifier Number (RIN)

    The Department of Transportation assigns a regulation identifier 
number (RIN) to each regulatory action listed in the Unified Agenda of 
Federal Regulations. The Regulatory Information Service Center 
publishes the Unified Agenda in April and October of each year. You may 
use the RIN contained in the heading at the beginning of this document 
to find this action in the Unified Agenda.

Comments

How Do I Prepare and Submit Comments?

    Your comments must be written and in English. To ensure that your 
comments are correctly filed in the Docket, please include the docket 
number of this document in your comments.
    Your comments must not be more than 15 pages long. (49 CFR 553.21). 
We established this limit to encourage you to write your primary 
comments in a concise fashion. However, you may attach necessary 
additional documents to your comments. There is no limit on the length 
of the attachments.
    Please submit two copies of your comments, including the 
attachments, to Docket Management at the address given above under 
ADDRESSES.
    In addition, given the statutory deadline of November 1, 2001, for 
issuance of the final rule, for those comments of 4 or more pages in 
length, we request that you send 10 additional copies, as well as one 
copy on computer disc, to: Mr. George Soodoo, Office of Crash Avoidance 
Standards, National Highway Traffic Safety Administration, 400 Seventh 
Street, SW., Washington, DC 20590. We emphasize that this is not a 
requirement. However, we ask that you do this to aid us in expediting 
our review of all comments. The copy on computer disc may be in any 
format, although we would prefer that it be in WordPerfect 8 or Word 
2000.
    You may also submit your comments to the docket electronically by 
logging onto the Dockets Management System website at http://dms.dot.gov. Click on ``Help & Information'' or ``Help/Info'' to obtain 
instructions for filing the document electronically.

How Can I Be Sure That My Comments Were Received?

    If you wish Docket Management to notify you upon its receipt of 
your comments, enclose a self-addressed, stamped postcard in the 
envelope containing your comments. Upon receiving your comments, Docket 
Management will return the postcard by mail.

How Do I Submit Confidential Business Information?

    If you wish to submit any information under a claim of 
confidentiality, you should submit three copies of your complete 
submission, including the information you claim to be confidential 
business information, to the Chief Counsel, NHTSA, at the address given 
above under FOR FURTHER INFORMATION CONTACT. In addition, you should 
submit two copies, from which you have deleted the claimed confidential 
business information, to Docket Management at the address given above 
under ADDRESSES. When you send a comment containing information claimed 
to be confidential business information, you should include a cover 
letter setting forth the information specified in our confidential 
business information regulation. (49 CFR part 512.)

Will the Agency Consider Late Comments?

    We will consider all comments that Docket Management receives 
before the close of business on the comment closing date indicated 
above under DATES. To the extent possible, we will also consider 
comments that Docket Management receives after that date. If Docket 
Management receives a comment too late for us to consider it in 
developing a final rule (assuming that one is issued), we will consider 
that comment as an informal suggestion for future rulemaking action.

How Can I Read the Comments Submitted by Other People?

    You may read the comments received by Docket Management at the 
address

[[Page 39000]]

given above under ADDRESSES. The hours of the Docket are indicated 
above in the same location.
    You may also see the comments on the Internet. To read the comments 
on the Internet, take the following steps:
    1. Go to the Docket Management System (DMS) Web page of the 
Department of Transportation (http://dms.dot.gov/).
    2. On that page, click on ``search.''
    3. On the next page (http://dms.dot.gov/search/), type in the four-
digit docket number shown at the beginning of this document. Example: 
If the docket number were ``NHTSA-1998-1234,'' you would type ``1234.'' 
After typing the docket number, click on ``search.''
    4. On the next page, which contains docket summary information for 
the docket you selected, click on the desired comments. You may 
download the comments. Although the comments are imaged documents, 
instead of word processing documents, the ``pdf'' versions of the 
documents are word searchable.
    Please note that even after the comment closing date, we will 
continue to file relevant information in the Docket as it becomes 
available. Further, some people may submit late comments. Accordingly, 
we recommend that you periodically check the Docket for new material.

List of Subjects in 49 CFR Part 571

    Imports, Motor vehicle safety, Reporting and recordkeeping 
requirements, Tires.

    In consideration of the foregoing, NHTSA proposes to amend 49 CFR 
part 571 as follows:

PART 571--FEDERAL MOTOR VEHICLE SAFETY STANDARDS

    1. The authority citation for part 571 would continue to read as 
follows:

    Authority: 49 U.S.C. 322, 30111, 30115, 30117, and 30166; 
delegation of authority at 49 CFR 1.50.

    2. In section 571.101, in Table 2, two new entries would be added 
at the end of the table to read as follows:


Sec. 571.101  Standard No. 101; controls and displays.

* * * * *

                              Table 2.--Identification and Illustration of Displays
----------------------------------------------------------------------------------------------------------------
            Column 1                   Column 2            Column 3            Column 4            Column 5
----------------------------------------------------------------------------------------------------------------
Display.........................  Telltale Color....  Identifying Words   Identifying Symbol  Illumination.
                                                       or Abbreviation.
----------------------------------------------------------------------------------------------------------------

* * * * *

BILLING CODE 4910-59-P

[[Page 39001]]

[GRAPHIC] [TIFF OMITTED] TP26JY01.001


[[Page 39002]]


[GRAPHIC] [TIFF OMITTED] TP26JY01.002

BILLING CODE 4910-59-C

    3. Section 571.138 would be added to read as follows:


Sec. 571.138  Standard No. 138; tire pressure monitoring systems.

[FIRST ALTERNATIVE FOR S1 THROUGH S6]
    S1. Purpose and scope. This standard specifies performance 
requirements for tire pressure monitoring systems to prevent 
significant under-inflation of tires and the resulting safety problems.
    S2. Application. This standard applies to passenger cars, 
multipurpose passenger vehicles, trucks, and buses that have a gross 
vehicle weight rating of 4,536 kilograms (10,000 pounds) or less, and 
that are manufactured on or after [The date that is two years after 
date of publication of final rule.].
    S3. Definitions. The following definitions apply to this standard:
    Lightly loaded vehicle weight means unloaded vehicle weight, plus 
up to 400 pounds (including test driver and instrumentation).
    Significantly under-inflated means any inflation pressure that is 
equal to or less than either the pressure 20 percent below the vehicle 
manufacturer's recommended cold inflation pressure, or the pressure 
specified in the 3rd column of Table 1 of this standard for the 
corresponding type of tire, whichever is higher.
    Tire pressure monitoring system means a system that detects when 
one or more of a vehicle's tires is significantly under-inflated and 
illuminates the low tire pressure warning telltale.
    S4. Requirements.
    S4.1  General. Each vehicle must be equipped with a tire pressure 
monitoring system that meets the requirements of S4.2 and S4.3 of this 
standard under the test conditions of S5 and the test procedures of S6.
    S4.2  Low tire pressure warning telltale.
    S4.2.1  Each tire pressure monitoring system must include a low 
tire pressure warning telltale that:
    (a) Is mounted inside the occupant compartment in clear view of the 
driver;
    (b) Is identified by the symbol or words shown for the ``Low Tire 
Pressure Telltale'' in Table 2 of Standard No. 101 (Sec. 571.101);
    (c) Becomes illuminated not more than 10 minutes after any of the 
vehicle's tires becomes significantly under-inflated;
    (d) Remains illuminated as long as any of the vehicle's tires 
remains significantly under-inflated, and the ignition switch is in the 
``on'' (``run'') position, whether or not the engine is running; and
    (e) Can be deactivated, manually or automatically, only when all of 
the vehicle's tires cease to be significantly under-inflated.
    S4.2.2  In the case of a telltale that identifies which tires are 
significantly under-inflated, each tire in the symbol

[[Page 39003]]

for that telltale must illuminate when the tire it represents is 
significantly under-inflated.
    S4.3  Replacement tires/rims. Each tire pressure monitoring system 
must continue to meet the requirements of this standard when the 
vehicle's original tires or rims are replaced with any optional or 
replacement tire/rim size(s) recommended for the vehicle by the vehicle 
manufacturer.
    S4.4  Written instructions. The owner's manual in each vehicle must 
provide an image of the TPMS symbol with the following information, in 
English: ``When the TPMS warning light is lit, one of your tires is 
significantly under-inflated. You should stop and check your tires as 
soon as possible, and inflate them to the proper pressure as indicated 
on the vehicle's tire inflation placard. Driving on an under-inflated 
tire causes the tire to overheat and can eventually lead to tire 
failure. Under-inflation also reduces fuel efficiency and tire tread 
life, and may affect the vehicle's handling and stopping ability.'' 
Each vehicle manufacturer may, at its discretion, provide additional 
information about the significance of the low tire pressure warning 
telltale illuminating and description of corrective action to be 
undertaken.
    S5. Test conditions.
    S5.1  Ambient temperature. The ambient temperature is between 
0 deg.C (32 deg.F) and 40 deg.C (104 deg.F).
    S5.2  Road test surface. Road tests are conducted on a dry, smooth 
roadway.
    S5.3  Vehicle conditions.
    S5.3.1  Test weight. The vehicle is tested at its lightly loaded 
vehicle weight and at its gross vehicle weight rating without exceeding 
any of its gross axle weight ratings.
    S5.3.2  Vehicle speed. The vehicle is tested at a speed between 50 
km/h (31.1 mph) and 100 km/h (62.2 mph).
    S6. Test procedures.
    (a) Inflate the vehicle's tires to the vehicle manufacturer's 
recommended cold inflation pressure.
    (b) Drive the vehicle between 50 km/h and 100 km/h for up to 20 
minute.
    (c) While driving within the speed range specified in paragraph 
S6(b) of this standard, deflate any tire or combination of the 
vehicle's tires until that tire or each of those tires is significantly 
under-inflated.
    (d) Continue to drive within the speed range specified in paragraph 
S6(b) of this standard. Record the elapsed time between the time when 
the vehicle's tire or combination of tires becomes significantly under-
inflated to the time the low tire pressure warning telltale is 
illuminated.
    (e) After the warning telltale illuminates, add pressure (if 
necessary) to the tire or combination of tires that was deflated such 
that that tire or each of those tires is one psi below the level of 
significant under-inflation. Check to see if the warning telltale 
remains illuminated. If the warning telltale remains on, attempt to 
manually reset the system in accordance with the written instructions 
provided by the vehicle manufacturer.
    (f) Repeat the test procedures in paragraphs 6(a) through (e) for 
each tire and rim combination recommended for the vehicle by the 
vehicle manufacturer.

Tables to Sec. 571.138

                    Table 1.--Low Tire Pressure Warning Telltale--Minimum Activation Pressure
----------------------------------------------------------------------------------------------------------------
                                                   Maximum inflation minimum               Pressure activation
                                       ------------------------------------------------         pressure
               Tire type                                                               -------------------------
                                                 (kPa)                   (psi)             (kPa)        (psi)
----------------------------------------------------------------------------------------------------------------
P-metric--Standard Load...............  240,..................  35,...................          140           20
                                        300, or...............  44, or................          140           20
                                        350...................  51....................          140           20
----------------------------------------------------------------------------------------------------------------
P-metric--Extra Load..................  280 or................  41 or.................          160           23
                                        340...................  49....................          160           23
----------------------------------------------------------------------------------------------------------------
Load Range C..........................  350...................  51....................          200           29
----------------------------------------------------------------------------------------------------------------
Load Range D..........................  450...................  65....................          260           38
----------------------------------------------------------------------------------------------------------------
Load Range E..........................  600...................  87....................          350           51
----------------------------------------------------------------------------------------------------------------


[SECOND ALTERNATIVE FOR S1 THROUGH S6]
    S1. Purpose and scope. This standard specifies performance 
requirements for tire pressure monitoring systems to prevent 
significant under-inflation of tires and the resulting safety problems.
    S2. Application. This standard applies to passenger cars, 
multipurpose passenger vehicles, trucks, and buses that have a gross 
vehicle weight rating of 4,536 kilograms (10,000 pounds) or less, and 
that are manufactured on or after [The date that is two years after 
date of publication of final rule.].
    S3. Definitions. The following definitions apply to this standard:
    Lightly loaded vehicle weight means unloaded vehicle weight plus up 
to 400 pounds (including test driver and instrumentation).
    Significantly under-inflated means any inflation pressure that is 
equal to or less than either the pressure 25 percent below the vehicle 
manufacturer's recommended cold inflation pressure, or the pressure 
specified in the 3rd column of Table 1 of this standard for the 
corresponding type of tire, whichever is higher.
    Tire pressure monitoring system means a system that detects when 
one or more of a vehicle's tires is significantly under-inflated and 
illuminates the low tire pressure warning telltale.
    S4. Requirements.
    S4.1  General. Each vehicle must be equipped with a tire pressure 
monitoring system that meets the requirements of S4.2 and S4.3 of this 
standard under the test conditions of S5 and the test procedures of S6.
    S4.2  Low tire pressure warning telltale.
    S4.2.1  Each tire pressure monitoring system must include a low 
tire pressure warning telltale that:
    (a) Is mounted inside the occupant compartment in clear view of the 
driver;
    (b) Is identified by the symbol or words shown for the ``Low Tire 
Pressure Telltale'' in Table 2 of Standard No. 101 (Sec. 571.101);
    (c) Becomes illuminated not more than 10 minutes after any of the

[[Page 39004]]

vehicle's tires becomes significantly under-inflated;
    (d) Remains illuminated as long as any of the vehicle's tires 
remains significantly under-inflated, and the ignition switch is in the 
``on'' (``run'') position, whether or not the engine is running; and
    (e) Can be deactivated, manually or automatically, only when all of 
the vehicle's tires cease to be significantly under-inflated.
    S4.2.2  In the case of a telltale that identifies which tires are 
significantly under-inflated, each tire in the symbol for that telltale 
must illuminate when the tire it represents is significantly under-
inflated.
    S4.3  Replacement tires/rims. Each tire pressure monitoring system 
must continue to meet the requirements of this standard when the 
vehicle's original tires or rims are replaced with any optional or 
replacement tire/rim size(s) recommended for the vehicle by the vehicle 
manufacturer.
    S4.4  Written instructions. The owner's manual in each vehicle must 
provide an image of the TPMS symbol with the following information, in 
English: ``When the TPMS warning light is lit, one of your tires is 
significantly under-inflated. You should stop and check your tires as 
soon as possible, and inflate them to the proper pressure as indicated 
on the vehicle's tire inflation placard. Driving on an under-inflated 
tire causes the tire to overheat and can eventually lead to tire 
failure. Under-inflation also reduces fuel efficiency and tire tread 
life, and may affect the vehicle's handling and stopping ability.'' 
Each vehicle manufacturer may, at its discretion, provide additional 
information about the significance of the low tire pressure warning 
telltale illuminating and description of corrective action to be 
undertaken.
    S5. Test conditions.
    S5.1  Ambient temperature. The ambient temperature is between 
0 deg.C (32 deg.F) and 40 deg.C (104 deg.F).
    S5.2  Road test surface. Road tests are conducted on a dry, smooth 
roadway.
    S5.3  Vehicle conditions.
    S5.3.1  Test weight. The vehicle is tested at its lightly loaded 
vehicle weight and at its gross vehicle weight rating without exceeding 
any of its gross axle weight ratings.
    S5.3.2  Vehicle speed. The vehicle is tested at a speed between 50 
km/h (31.1 mph) and 100 km/h (62.2 mph).
    S6. Test procedures.
    (a) Inflate the vehicle's tires to the vehicle manufacturer's 
recommended cold inflation pressure.
    (b) Drive the vehicle between 50 km/h and 100 km/h for up to 20 
minutes.
    (c) While driving within the speed range specified in paragraph 
S6(b) of this standard, deflate any tire or combination of the 
vehicle's tires, up to a total of three tires, until that tire or each 
of those tires is significantly under-inflated.
    (d) Continue to drive within the speed range specified in paragraph 
S6(b) of this standard. Record the elapsed time between the time when 
the vehicle's tire or combination of tires becomes significantly under-
inflated to the time the low tire pressure warning telltale is 
illuminated.
    (e) After the warning telltale illuminates, add pressure (if 
necessary) to the tire or combination of tires that was deflated such 
that that tire or each of those tires is one psi below the level of 
significant under-inflation. Check to see if the warning telltale 
remains illuminated. If the warning telltale remains on, attempt to 
manually reset the system in accordance with the written instructions 
provided by the vehicle manufacturer.
    (f) Repeat the test procedures in paragraphs 6(a) through (e) for 
each tire and rim combination recommended for the vehicle by the 
vehicle manufacturer.

Tables to Sec. 571.138

                    Table 1.--Low Tire Pressure Warning Telltale--Minimum Activation Pressure
----------------------------------------------------------------------------------------------------------------
                                                  Maximum inflation pressure               Minimum activation
                                       ------------------------------------------------         pressure
               Tire type                                                               -------------------------
                                                 (kPa)                   (psi)             (kPa)        (psi)
----------------------------------------------------------------------------------------------------------------
P-metric--Standard Load...............  240,..................  35,...................          140           20
                                        300, or...............  44, or................          140           20
                                        350...................  51....................          140           20
----------------------------------------------------------------------------------------------------------------
P-metric--Extra Load..................  280 or................  41 or.................          160           23
                                        340...................  49....................          160           23
----------------------------------------------------------------------------------------------------------------
Load Range C..........................  350...................  51....................          200           29
----------------------------------------------------------------------------------------------------------------
Load Range D..........................  450...................  65....................          260           38
----------------------------------------------------------------------------------------------------------------
Load Range E..........................  600...................  87....................          350           51
----------------------------------------------------------------------------------------------------------------


    Issued: July 23, 2001.
Stephen R. Kratzke,
Associate Administrator for Safety Performance Standards.
[FR Doc. 01-18637 Filed 7-23-01; 1:51 pm]
BILLING CODE 4910-59-P