[Federal Register Volume 70, Number 96 (Thursday, May 19, 2005)]
[Proposed Rules]
[Pages 28888-28895]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 05-9989]


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DEPARTMENT OF TRANSPORTATION

National Highway Traffic Safety Administration

49 CFR Part 571

[Docket No. NHTSA-2005-20967]


Federal Motor Vehicle Safety Standards

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

ACTION: Denial of petition for rulemaking.

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SUMMARY: This document denies a petition from the Rubber Manufacturers 
Association (RMA) to conduct rulemaking to amend the Federal motor 
vehicle safety standard on tire selection and rims to require 
manufacturers of new motor vehicles to establish a recommended cold 
inflation pressure (placard pressure) for their vehicles using a tire 
pressure reserve. The tire pressure reserve would be based on the 
minimum pressure the RMA believes is necessary to support the vehicle's 
maximum load at the activation pressure of the installed tire pressure 
monitoring system (TPMS). The agency has decided to deny the petition 
because neither the RMA's nor the agency's data demonstrate a safety 
need for such a requirement.

FOR FURTHER INFORMATION CONTACT: The following persons at the National 
Highway Traffic Safety Administration, 400 Seventh Street, SW., 
Washington, DC, 20590: For technical issues: Mr. George Soodoo or Mr. 
Ezana Wondimneh, Office of Crash Avoidance Standards (Telephone: 202-
366-2720) (Fax: 202-366-7002). For legal issues: Mr. Eric Stas, Office 
of the Chief Counsel (Telephone: 202-366-2992) (Fax: 202-366-3820).

SUPPLEMENTARY INFORMATION:

I. Executive Summary

A. The RMA's Petition

    The Rubber Manufacturers Association \1\ submitted a petition for 
rulemaking \2\ to NHTSA to amend Federal Motor Vehicle Safety Standard 
(FMVSS) No. 110, Tire Selection and Rims, to include a tire pressure 
reserve sufficient to permit the tires to carry the vehicle maximum 
load at the threshold activation pressure for illumination of the low 
tire pressure telltale (a lighted indicator) under FMVSS No. 138, Tire 
Pressure Monitoring Systems. Pursuant to FMVSS No. 138, the under-
inflation warning threshold for the TPMS is set at 25% below the 
vehicle manufacturer's recommended cold inflation pressure or a minimum 
activation pressure corresponding to the type of tire, whichever is 
higher.
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    \1\ The Rubber Manufacturers Association is a national trade 
organization representing tire and rubber manufacturers in the 
United States. Its membership includes: (1) Bridgestone/Firestone 
Americas Holdings, L.L.C, (2) Continental North America, Inc, (3) 
Cooper Tire and Rubber Company, (4) The Goodyear Tire and Rubber 
Company, (5) Michelin North America, Inc., (6) Pirelli Tire North 
America, and (7) Yokohama Tire Corporation.
    \2\ Docket No. NHTSA-2005-20967-1.
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    The Tire and Rim Association (TRA) establishes and publishes 
guidelines, by tire size, for recommended tire load and tire pressure. 
The TRA guidelines, along with similar publications by other specified 
tire industry organizations, incorporate detailed tables that are used 
by vehicle manufacturers when deciding on original equipment tires and 
the recommended tire pressure to place on the vehicle's tire placard. 
The tire placard is located on the driver's side B-pillar and is 
intended to inform vehicle owners of the proper tire inflation pressure 
level.
    In addition to the tire placard information, pursuant to a 
statutory mandate, the agency has recently issued a Final Rule 
establishing requirements to ensure that vehicle owners are informed 
when a tire is significantly under-inflated. These systems, known as 
tire pressure monitoring systems, will detect and warn consumers within 
20 minutes after a tire's inflation pressure drops to 25% below the 
vehicle manufacturer's recommended inflation level. The primary 
function of a TPMS is to detect under-inflation caused by slow leaks 
that may otherwise go unnoticed. TPMS are not substitutes for proper 
tire maintenance. Instead, they provide a supplemental system to assist 
in informing vehicle owners when maintenance is needed.
    The RMA's petition postulates that the pressure in a vehicle's 
tires at maximum load may fall below the recommended value in the TRA 
tables before the TPMS warning telltale provides its alert. According 
to the RMA, the tables specify the minimum pressure that should be 
recommended for each tire at the vehicle's maximum load. Following this 
reasoning, if a vehicle manufacturer recommends a placard pressure with 
less than a 25% margin above what is required to support the vehicle's 
maximum load, the tires could conceivably fall below the TRA specified 
value before the TPMS warning telltale illuminates. The RMA asserted 
that a vehicle driven under such conditions (below TRA specified 
values) is overloading its tires and that this may lead to tire 
degradation and, ultimately, to tire failure.
    The RMA cited a recent NHTSA study finding that 26% of passenger 
cars--and 29% of pick-up trucks, sport utility vehicles, and vans--had 
at least one tire that was under-inflated by at least 25% below placard 
pressure.\3\ The RMA also submitted calculations from a sample of 100 
vehicles (model years (MY) 1997 to 2003) indicating that 61% would not 
have sufficient pressure reserve at maximum load (based on the TRA 
tables) if the vehicle's tire pressure were to fall to 25% below 
placard pressure.\4\ Finally, the RMA relied on a telephone survey of 
motorists, which reported that 67% of those surveyed would be less 
concerned about checking their tire pressure if their vehicles were 
equipped with a TPMS.
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    \3\ Docket No. NHTSA-2000-8572-74.
    \4\ We note that the RMA submitted calculations based upon two 
sets of data that together totaled 100 vehicles. For the purposes of 
this notice, we have combined these two data sets as a single 
weighted average. We have done this both for ease of use and because 
the distinctions between those data sets do not impact our 
resolution of the RMA's petition.
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    From these data, the RMA concluded that NHTSA's tire standards must 
be amended to provide a reserve load so that drivers are not lulled 
into a false sense of security that may lead them to rely exclusively 
on the TPMS. The RMA argued that the TPMS could encourage drivers to 
neglect proper tire maintenance, leading in turn to an increased risk 
of driving on overloaded tires and resulting tire failures.

B. NHTSA's Research To Consider the Petition

    The Secretary of Transportation has delegated rulemaking authority 
under 49 U.S.C. Chapter 301 to prescribe motor vehicle safety standards 
to NHTSA.\5\ However, in order to issue such standards, the agency must 
make a determination that the standard (or amendment to an existing 
standard) is practicable, meets the need for motor vehicle safety, and 
is stated in objective terms.\6\ Consistent with this statutory 
directive, NHTSA's regulations related to the requirements for 
petitions for rulemaking state that the petition must ``[s]et forth 
facts which it is claimed

[[Page 28889]]

establish that an order is necessary.'' \7\ If the above criteria have 
not been met, the agency may not issue a final rule. Accordingly, the 
RMA's petition must be analyzed in the context of whether sufficient 
evidence exists as would permit rulemaking to proceed.
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    \5\ See 49 CFR 1.50.
    \6\ 49 U.S.C. 30111(a).
    \7\ 49 CFR 552.4(c).
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    In considering the RMA's petition, we reviewed our research 
relating to whether TPMSs may affect attitudes toward tire maintenance 
and conducted a comprehensive new study to assess whether there is any 
correlation between reserve load and real world tire failures.
    Because it is possible that some drivers might postpone tire 
pressure checks until the TPMS warning telltale illuminates, we decided 
to study actual driver behavior by examining the incidence of inflation 
pressure checks (as indicated by tire inflation levels) for both TPMS-
equipped vehicles and non-equipped peer vehicles.\8\ The study examined 
2,316 vehicles, 1,259 of which were equipped with TPMSs (213 direct 
TPMSs and 1,046 indirect TPMSs).\9\
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    \8\ Docket No. NHTSA-2005-20967-4.
    \9\ There are two types of TPMSs currently available, direct 
TPMSs and indirect TPMSs. Direct TPMSs have a pressure sensor in 
each wheel that transmits pressure information to a receiver. In 
contrast, indirect TPMSs do not have tire pressure sensors, but 
instead rely on the wheel speed sensors, typically a component of an 
anti-lock braking system, to detect and compare differences in the 
rotational speed of a vehicle's wheels, which correlate to 
differences in tire pressure.
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    We also studied whether a 25% reserve load requirement is likely to 
have an impact on real world tire failures. Through Special Orders, we 
collected detailed data from both tire and vehicle manufacturers to 
compare the risk of tire failure as a function of tire pressure 
reserve. The data included details of tire failures reported as claims 
to tire manufacturers and the distribution in the fleet of pressure 
reserves as tallied by vehicle manufacturers.
    Our purpose was to study how the risk of tire failure varied with 
pressure reserve for original equipment tires on light vehicles. We 
used a variety of statistical techniques (including simple correlations 
and failure-time models) to search for a pattern of failure. We sought 
and received input on our analytic approach from the Consumer Product 
Safety Commission and the Department of Transportation's Bureau of 
Transportation Statistics.

C. Summary of the Agency's Findings

    Having reviewed the RMA's data and positions, and having conducted 
our own analysis into the issues raised in the petition, we have 
concluded that the data do not substantiate a safety need to establish 
such a tire pressure reserve requirement under FMVSS No. 110. We have 
reached this result because:
     The RMA's data regarding the impacts of TPMS installation 
were based on the results of a self-reported telephone survey and did 
not involve an objective analysis of actual vehicle operating 
conditions through direct observation (i.e., by checking tire pressure 
levels). NHTSA's survey results, which did involve direct measurement 
of vehicles' tire pressure levels, found that the existence of TPMSs in 
new vehicles would not cause drivers to neglect routine tire 
maintenance.
     The RMA's petition gives the mistaken impression that 
vehicles are regularly loaded to their maximum vehicle weight. In fact, 
most vehicle trips involve the driver alone, without significant 
vehicle cargo. NHTSA s data show that, under normal loading conditions 
with tires inflated 25% below placard pressure, only 11% of vehicles 
would have overloaded tires.\10\
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    \10\ Docket No. NHTSA-2005-20967-2, p. 27.
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     Our research demonstrates that even for vehicles found to 
have tires under-inflated by 25% or more, tire failures are rare 
events. In a recent study,\11\ the total number of tire failure claims 
reported to the agency was 52 per one million vehicles or a lifetime 
failure rate of approximately 0.0052 percent for non-recalled 
tires.\12\
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    \11\ Docket No. NHTSA-2005-20967-2.
    \12\ Although there is a higher rate for tire failure claims 
when recalled tires are included, we believe that many failures in 
those cases would be a product of a defect in the tire itself, 
rather than a problem associated with tire pressure reserve. 
Furthermore, it should also be noted that many of reported tire 
failures may be caused by other factors not related to tire pressure 
reserve, such as vehicles being operated with grossly under-inflated 
or overloaded tires, excessively worn high mileage tires, or 
vehicles being operated in hot climates.
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     Agency data suggest that the presence or absence of a tire 
pressure reserve has little bearing on tire failures, a finding which 
goes to the heart of the RMA's petition. Specifically, NHTSA examined 
available data to see whether a high tire pressure reserve resulted in 
fewer tire failures. We found that the data for certain vehicles with a 
tire pressure reserve suggested (but did not establish) a lower 
incidence of tire failures. However, in other cases, the data for 
vehicles with a tire pressure reserve suggested (but again did not 
establish) a higher incidence of tire failures. Not only were the 
results conflicting, but in none of those cases were the results 
statistically significant.
     RMA's calculations, which the RMA uses to characterize the 
sufficiency of the tire pressure at maximum vehicle load, are based 
solely upon deviation from the values reported in the TRA tables. The 
RMA has not demonstrated the likelihood that operation of a vehicle at 
tire pressures somewhat below these values is likely to result in tire 
failure. In light of the above, the available data suggest that the 
problem articulated in the RMA's petition is essentially a theoretical 
one and is inconsistent with real world data that show a relatively 
small number of actual tire failures.
     We expect that a tire pressure reserve requirement for new 
light vehicles would have major technical and economic ramifications 
for the automotive industry, with an estimated annual cost of $132 
million. Given the absence of a demonstrated safety benefit, the data 
do not support passing these relatively large costs on to consumers. We 
do not agree with the assertion that vehicle manufacturers could 
accommodate a 25% tire pressure reserve load requirement, and incur no 
substantial cost, by raising the recommended tire inflation pressures 
or by specifying larger tires with more load carrying capacity for 
their vehicles.

D. Conclusion

    In light of the above, the agency has concluded that: (1) The RMA 
has not provided sound evidence to suggest that installation of a TPMS 
will mislead consumers into believing that their tires are properly 
inflated whenever the TPMS warning telltale is not illuminated; (2) the 
RMA's data have not demonstrated that vehicles with little or no 
pressure reserve have a higher rate of failure in the field compared 
with vehicles having a high tire pressure reserve; and (3) NHTSA's own 
data demonstrate that a tire pressure reserve requirement, as 
recommended by the RMA, would not be expected to result in a measurable 
safety benefit by reducing real world tire failures. Accordingly, we 
are denying the RMA's petition.

II. Background

    In 2000, following numerous motor vehicle fatalities involving 
failures of defective tires, Congress passed the Transportation Recall 
Enhancement, Accountability and Documentation (TREAD) Act.\13\ Among 
other things, the TREAD Act directed NHTSA to improve the FMVSSs for 
tires and to issue a regulation to require installation of TPMSs in new 
vehicles. In response,

[[Page 28890]]

NHTSA upgraded several safety standards, including FMVSS No. 110, Tire 
Selection and Rims, and developed FMVSS No. 138, Tire Pressure 
Monitoring Systems, a new standard mandating the installation of 
automated devices to warn drivers operating motor vehicles with 
significantly under-inflated tires.
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    \13\ Pub. L. No. 106-414, 114 Stat. 1800 (2000).
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    As initially promulgated, FMVSS No. 138 provided for two compliance 
options. Under either option, the TPMS would illuminate a warning 
telltale when tire pressure dropped below the higher of either a 
threshold value (determined as a percentage below placard pressure) or 
a minimum activation pressure listed in the standard. Option One 
required a TPMS with a 25% under-inflation warning capability for any 
combination of tires, up to a total of four tires. Option Two required 
a TPMS with a 30% under-inflation warning capability for any one 
tire.\14\
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    \14\ 67 FR 38704 (June 5, 2002).
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    On August 6, 2003, the United States Court of Appeals for the 
Second Circuit vacated the June 2002 final rule.\15\ The Court held 
that one option, which had a 30%-below-placard threshold, was unlawful 
because it would permit systems that could not monitor all four of a 
vehicle's tires. The agency has recently published a final rule 
adopting a revised FMVSS No. 138 that is consistent with the court's 
opinion (i.e., requiring a TPMS with a four-tire, 25% under-inflation 
detection capability).\16\ The Court proceedings affected the timing 
and content of our TPMS rule, but not the analysis of the issues 
relevant to the RMA's petition.
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    \15\ See Public Citizen v. Mineta, 340 F.3d 39 (2d Cir. 2003).
    \16\ See 70 FR 18136, (April 8, 2005). Docket No. NHTSA-2005-
20586-1.
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    As part of developing the upgraded FMVSS No. 110 and the new FMVSS 
No. 138, the agency evaluated tire loading limits and tire pressure 
reserves for motor vehicles, as well as how often and why vehicles are 
driven with significantly under-inflated tires. We set forth below a 
summary of how the agency addressed these topics in order to provide 
background for understanding the agency's analysis of the RMA petition 
and the reasons for its denial.

A. Tire Pressure Reserve

    FMVSS No. 110 was first issued in 1971. It mandates among other 
things that all passenger cars sold in the United States be equipped 
with tires that are capable of carrying the vehicle's maximum loaded 
vehicle weight at the manufacturer's recommended cold inflation 
pressure (vehicle placard pressure). Multipurpose passenger vehicles, 
trucks, buses and trailers must be fitted with tires that are capable 
of supporting the vehicle's gross axle weight rating (GAWR).\17\ In 
most cases, vehicle manufacturers meet these requirements by consulting 
standardized tables for tire size, loading, and inflation pressure 
published by the Tire and Rim Association or other international tire 
industry organizations.\18\
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    \17\ This requirement was adopted from FMVSS No. 120, Tire 
Selection and Rims for Motor Vehicles Other Than Passenger Cars. 
Before TREAD Act related upgrades were made (which also consolidated 
NHTSA's tire standards), passenger cars, and non-passenger cars 
regardless of their gross vehicle weight rating (GVWR), were covered 
by FMVSS Nos. 110 and 120 respectively.
    \18\ Paragraph S4.3.1(c) of FMVSS No. 110 permits the use of 
standard tire pressure/load tables contained in publications listed 
in paragraph S4.4.1(b) of FMVSS No. 109 that are current at the date 
of manufacture of the tire or any later date. Specifically, 
publications by any of the following international industrial 
organizations may be used: (1) The Tire and Rim Association, (2) The 
European Tyre and Rim Technical Organization, (3) Japan Automobile 
Tire Manufacturers' Association, Inc., (4) Tyre & Rim Association of 
Australia, (5) Associacao Latino Americana de Pneus e Aros Brazil, 
or (6) The South African Bureau of Standards.
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    Vehicle manufacturers may, at their discretion, specify a higher 
placard pressure for the tires fitted to their products than that 
provided by the TRA tables to support the vehicle's maximum load. This 
additional tire pressure is known as ``tire pressure reserve.'' Within 
bounds, an increase in tire pressure results in an increase in load 
carrying capacity. The extra load carrying capacity realized, because 
of the additional tire pressure, is called the ``tire load reserve.''
    FMVSS No. 110 also includes a requirement for a tire pressure 
reserve based on vehicle normal load. ``Vehicle normal load'' is that 
load on an individual tire that is determined by distributing to each 
axle its share of the curb weight, accessory weight, and occupant 
weight and dividing the result by two. The number of occupants used to 
determine the ``normal load'' is defined in FMVSS No. 110 as two 
persons for a vehicle with four seating positions, and three persons 
for a vehicle with five seating positions. The current standard 
requires that the vehicle normal load on a tire shall not be greater 
than 88% of the tire's maximum load rating as marked on the tire 
sidewall.
    NHTSA published a final rule upgrading the standards applicable to 
tires on June 26, 2003 (68 FR 38116).\19\ The upgraded version of FMVSS 
No. 110 specifies that the vehicle normal load on each tire must not 
exceed 94% of the tire's load rating at the placard pressure for that 
tire. The agency noted in the preamble of the final rule for the tire 
performance upgrade that this change would provide safety improvements 
without necessitating extensive and high cost vehicle redesigns:
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    \19\ The June 23, 2003 final rule pertained to FMVSS No. 109, 
New Pneumatic Bias Ply and Certain Specialty Tires, FMVSS No. 110, 
Tire Selection and Rims for Motor Vehicles with a GVWR of 4,536 
Kilograms (10,000 Pounds) or Less, FMVSS No. 119, New Pneumatic 
Tires for Motor Vehicles with a GVWR of More Than 4,536 Kilograms 
(10,000 Pounds) and Motorcycles, FMVSS No. 120, Tire Selection and 
Rims for Motor Vehicles with a GVWR of More Than 4,536 Kilograms 
(10,000 Pounds), and FMVSS No. 139, New Pneumatic Radial Tires for 
Light Vehicles.

    [V]ehicle manufacturers will be required to insure that the tire 
reserve load corresponds with the tire's load carrying capabilities 
when the tire is inflated to the vehicle manufacturers recommended 
cold tire inflation pressure rather than the tire manufacturer's 
maximum cold inflation pressure shown on the tire sidewall. The 94% 
figure was chosen to approximate closely the load reserve that 
results from the current requirement of 88% based on the load rating 
at the tire's maximum inflation pressure.
    By specifying a 94% value based on vehicle normal load, the 
agency is addressing the vehicle industry's concerns that a 
significant number of vehicles would otherwise need to be redesigned 
to accommodate larger tire sizes, while aiming to reflect more 
accurately actual vehicle loading conditions of vehicles by 
requiring that each vehicle manufacturer select the appropriate 
reserve load for that vehicle. The agency has recently conducted a 
FMVSS No. 110 vehicle normal load evaluation and has concluded that 
almost all light vehicles could meet a revised criteria for load 
reserve based on 94% of placard pressure with only a minor increase, 
e.g., 1 or 2 psi, in this listed inflation pressure to accommodate 
the new requirement.\20\
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    \20\ 68 FR 38116, 38141 (June 26, 2003).

    This change in calculation of vehicle normal load is intended to 
more accurately reflect the load based on the vehicle's placard 
pressure, which may vary from vehicle to vehicle, even when the same 
tires are used. As noted above, we anticipate that this change in the 
tire requirements may result in a tire pressure increase of 1-2 psi.

B. Tire Pressure Monitoring Systems

    Congress also mandated under the TREAD Act that NHTSA complete ``a 
rulemaking for a regulation to require a warning system in new motor 
vehicles to indicate to the operator when a tire

[[Page 28891]]

is significantly under-inflated'' (emphasis added). We note that 
Congress did not mandate a system that would signal whenever a tire 
deviated from placard pressure. To do so would likely result in 
nuisance warnings that eventually could cause drivers to ignore the 
TPMS.
    The agency commenced research studies to support the TPMS 
rulemaking. In February 2001, NHTSA's National Center for Statistics 
and Analysis (NCSA) conducted a national survey involving 11,530 
vehicles.\21\ The tire pressures of the study vehicles were recorded 
when they came into one of a number of randomly selected gas stations 
located across the country. NCSA found that 26% of passenger cars--and 
29% of pick-up trucks, SUVs and vans--had at least one tire that was 
underinflated by at least 25% below the placard pressure. This study 
was designed to assess the level of tire under-inflation for light 
vehicles on the road (i.e., the target population for the TPMS 
standard).
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    \21\ Docket No. NHTSA-2000-8572-74.
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    The agency established FMVSS No. 138, a new standard requiring 
light vehicles (i.e., vehicles with a GVWR of 4,536 kilograms (10,000 
pounds) or less) to be equipped with tire pressure monitoring systems 
that warn drivers when the air pressure in their tires has dropped by a 
specified percentage below the vehicle placard pressure or a minimum 
activation pressure listed in the standard that corresponds to the type 
of tire, whichever is higher. Prior to being vacated by court order, 
FMVSS No. 138 had two performance options for compliance. Option 1 
required a warning when any combination of one to four tires becomes 
under-inflated by 25%. Option 2 required a warning when one tire 
becomes under-inflated by 30%. As discussed in the June 2002 final 
rule, NHTSA's research suggested that illumination of the TPMS telltale 
at 25% or 30% tire under-inflation (or the minimum activation pressures 
in Table 1 of that rule) would provide a warning to the driver before 
any tire became ``significantly under-inflated.''
    On September 16, 2004, the agency published a new Notice of 
Proposed Rulemaking (NPRM) for FMVSS No. 138, Tire Pressure Monitoring 
Systems, which would re-establish the standard in a manner consistent 
with the Second Circuit's opinion (69 FR 55896). That NPRM proposed to 
mandate a TPMS that must be capable of monitoring the pressure in each 
tire and warning the vehicle operator when the tire pressure in any 
combination of one to four tires drops by 25% or more from the 
vehicle's placard pressure. That NPRM was followed by a final rule that 
adopted the four-tire, 25% under-inflation detection requirement as 
part of the standard.

III. The RMA Petition

    In July 2002, the Rubber Manufacturers Association petitioned NHTSA 
to initiate rulemaking to amend FMVSS No. 110, by establishing a new 
tire pressure reserve requirement for vehicles that have a GVWR of 
4,536 kilograms (10,000 pounds) or less. In its petition, the RMA 
requested that NHTSA require vehicle manufacturers to select tires for 
their vehicles that are capable of carrying the vehicle's maximum load 
\22\ even if under-inflated by up to 30% from the vehicle 
manufacturer's placard pressure. This percentage was chosen by the RMA 
because it corresponded to the minimum drop in tire inflation pressure 
before the TPMS warning is activated, under the less stringent of the 
two compliance options contained in the since-vacated June 2002 rule.
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    \22\ For purposes here and in the rest of this document, a 
vehicle's ``full load'' and ``maximum load'' are used 
interchangeably and mean a vehicle's maximum loaded vehicle weight 
in the case of passenger cars and the gross axle weight ratings for 
MPVs, trucks, buses, or trailers.
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    In its petition, the RMA stated that consumers who operate their 
vehicles in a fully-loaded condition, which do not have additional tire 
pressure (a tire pressure reserve) beyond what is required to support 
that load, may overload their tires if the inflation pressure decreases 
below the placard value. The RMA argued that extended operation of the 
vehicle in this worst-case scenario could result in tire failures.
    According to the RMA, for vehicles that have a tire pressure 
reserve, any reduction in tire inflation pressure that does not exceed 
that reserve amount would be inconsequential, as the tires would retain 
sufficient load carrying capacity (based on the TRA tables) for the 
vehicle's maximum load. However, the RMA argued that in practice, 
vehicle manufacturers sometimes set a pressure reserve only slightly 
above the load-pressure values provided in the TRA tables, which means 
that a tire's pressure may drop below that value prior to reaching the 
inflation pressure level that would trigger the TPMS low pressure 
warning lamp.
    The RMA further asserted that existing reserve requirements under 
NHTSA's current tire standards are inadequate to address this problem. 
Instead, by requiring a tire pressure reserve that is at least the same 
amount as the decrease in tire pressure that activates the TPMS 
telltale, the petitioner argued that vehicle operators would always 
receive warnings whenever tire pressures fall below the pressure 
required to support the vehicle's maximum load and that, as a result, 
the overall incidence of tire failures would be reduced.
    In its petition, the RMA asserted that unless NHTSA mandates a 
specified reserve load, its FMVSS would not adequately protect motor 
vehicle operators from the risks of driving on significantly under-
inflated tires. The petitioner claimed that its proposed requirement 
would address what it considers a ``serious deficiency'' in the TPMS 
rule, citing survey data from NCSA reflecting the percentages of 
sampled vehicles with underinflated tires. The RMA petition added: 
``There is a substantial risk that the new TPMS standards will, in 
practice, confuse or mislead consumers into believing that their tires 
are properly inflated whenever the TPMS warning is not illuminated.''
    To support its petition, the RMA provided calculated pressure 
reserve data, based on maximum vehicle loads, for a sample of 100 
vehicles from model years 1997 to 2003. The RMA data suggest that 61% 
of the sampled vehicles would not have sufficient reserve pressure at 
maximum load if equipped with a TPMS that activates when the vehicle's 
tire pressure falls by 25% from the placard pressure, and that 76% of 
the sampled vehicles would have insufficient reserve pressure if their 
tires were underinflated by 30% from the placard pressure. The RMA 
stated that most of the sampled vehicles would overload their tires if 
operated fully loaded and with them underinflated by 30% from the 
vehicle placard.
    The RMA petition also stated that most vehicles on the road today 
(61% or 76% depending on the TPMS warning threshold) could experience 
tire failures if drivers rely solely on TPMS warnings before 
maintaining their tire pressures. Specifically, the RMA argued that 
without an additional pressure reserve, drivers may operate their 
vehicles with tires underinflated from the recommended placard pressure 
by values ranging from zero to the warning threshold level before they 
receive a low tire pressure warning.

IV. Agency Analysis

A. Reduction in Proper Tire Maintenance

    The RMA petitioned NHTSA to require that vehicle manufacturers

[[Page 28892]]

select tires for their vehicles and provide a pressure reserve that 
would ensure the tires are capable of carrying the vehicle's maximum 
load even if underinflated by up to 30% from the vehicle placard 
pressure. The petitioner argued that the agency's TPMS rule (for 
systems capable of the now-vacated 30% under-inflation detection level 
or the current 25% under-inflation detection level) does not adequately 
protect motor vehicle operators from driving on significantly under-
inflated tires because there is a substantial risk that the TPMS 
standard will, in practice, confuse or mislead consumers into believing 
that their tires are properly inflated whenever the TPMS warning 
telltale is not illuminated.
    On August 19, 2003, the RMA provided comments to the NHTSA Docket 
on TPMS.\23\ The RMA indicated that its comments were, among other 
things, intended to supplement the materials submitted with its 
petition. Included in this submission were the results of a national 
consumer telephone survey of motorists' tire maintenance attitudes (700 
participants) and did not involve any tire pressure measurements. The 
RMA survey found that 67% of motorists would be less concerned with 
checking tire pressure if their vehicles were equipped with a TPMS.
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    \23\ Docket No. NHTSA-2000-8572-271.
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Agency Response
    The agency does not anticipate that consumers will come to believe 
that tire maintenance is unnecessary unless and until the TPMS warning 
telltale is illuminated. The agency believes that sufficient measures 
are in place to ensure that TPMSs operate as a supplement to regular 
tire maintenance, not as a substitute for it. Tire pressure monitoring 
systems are designed to detect slow and progressive reductions in tire 
pressure that may occur while driving (the standard requires the system 
to alert the driver within 20 minutes after the tire pressure has 
fallen below the requisite level) or when there is a significant 
decrease in tire pressure between regular tire pressure checks. The 
agency continues to mandate that tire pressure information be made 
clear to the vehicle owner on the driver's side B-pillar and in the 
owner's manual and that information on the importance of regular tire 
maintenance also be provided.
    For example, NHTSA's final rule for TPMS (S4.5) requires vehicle 
manufacturers to include specified owner's manual language that 
describes the importance of routine tire maintenance and the role of 
the TPMS. Specifically, the vehicle owner's manual must provide, in 
relevant part: ``Each tire, including the spare (if provided), should 
be checked monthly when cold and inflated to the inflation pressure 
recommended by the vehicle manufacturer on the vehicle placard or tire 
information label. * * * Please note that the TPMS is not a substitute 
for proper tire maintenance, and it is the driver's responsibility to 
maintain correct tire pressure, even if under-inflation has not reached 
the level to trigger illumination of the TPMS low tire pressure 
telltale.''
    NHTSA has also stressed the importance of proper tire maintenance 
as part of its consumer information program. For example, the agency 
has published and distributed a brochure on tire maintenance and repair 
titled ``Tire Safety: Everything Rides On It,'' with key highlights 
posted on the NHTSA Web site.\24\ Additional tire maintenance 
information is posted on NHTSA's Safercar.gov Web site.\25\
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    \24\ See http://www.nhtsa.dot.gov
    \25\ See http://www.safercars.gov/Tires/.
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    We are concerned with placing too heavy a reliance on the RMA's 
telephone survey because it did not involve actual observation of 
vehicle conditions (i.e., by checking tire pressure levels).\26\ RMA's 
survey only provided consumers' subjective opinions regarding tire 
maintenance. As a result, it is not possible to know whether the survey 
participants actually followed through with their claimed behavior. Nor 
did the RMA survey identify owners of TPMS-equipped vehicles, a group 
whose tire maintenance behavior may be most revealing when trying to 
assess the potential impact of TPMS on continuing maintenance.
---------------------------------------------------------------------------

    \26\ The RMA's petition also cited data from a July 2001 Bureau 
of Transportation Statistics (BTS) omnibus survey which found that 
65% of the respondents would be less concerned with routinely 
maintaining their tire pressures if their vehicles were equipped 
with a TPMS (see 67 FR 38704, 38718 (June 5, 2002)). However, like 
the RMA's telephone survey, this BTS survey did not include an 
observational component to determine whether consumers followed 
through on those opinions by decreasing their tire maintenance. 
Accordingly, we have the same concerns with the BTS survey as we do 
with the RMA's survey data.
---------------------------------------------------------------------------

    Other studies have more directly assessed the actual impact of 
TPMSs on tire inflation pressure levels, and they suggest that TPMSs 
may have a positive impact on tire pressure maintenance. The Alliance 
of Automobile Manufacturers (Alliance) submitted the results of a TPMS 
survey conducted by General Motors (GM) at its dealerships in 
Michigan.\27\ In that study, the tire pressures were measured on 267 
vehicles--211 vehicles with no TPMS, 32 vehicles with an indirect TPMS, 
and 24 vehicles with a direct TPMS.
---------------------------------------------------------------------------

    \27\ Docket No. NHTSA-2000-8572-246.
---------------------------------------------------------------------------

    The results of the General Motors real-world study indicated that 
the measured inflation pressure distribution for the vehicles with a 
direct TPMS was centered at 1% above placard pressure. The measured 
inflation pressure distribution for the vehicles with an indirect TPMS 
was centered at placard pressure, and the measured inflation pressure 
distribution for the vehicles with no TPMS was centered at 2% below 
placard pressure. The results of the study further indicated that TPMS-
equipped vehicle distributions are centered tightly around the placard 
pressure, and not close to the TPMS warning activation pressure level.
    In addition, NCSA recently completed a study on TPMSs that bears on 
the issue of tire inflation pressure maintenance. (A copy of the NCSA 
study can be found at Docket No. NHTSA-2005-20967-4.) In that study, 
data were collected on 2,316 vehicles ranging from passenger cars to 
light trucks. There were 213 vehicles equipped with direct TPMSs and 
1,046 vehicles equipped with indirect TPMSs. The remaining 1057 
vehicles were selected for use as baseline peer vehicles and were not 
equipped with any TPMS.
    The data were analyzed by comparing the recommended tire inflation 
pressure for each vehicle to actual measured tire pressure. The average 
level of under-inflation was found to be 11% for vehicles equipped with 
indirect TPMSs and 5% for those equipped with direct TPMSs. The peer 
comparison vehicles \28\ without TPMSs were found to have levels of 
under-inflation of 14% and 9%, respectively.
---------------------------------------------------------------------------

    \28\ PEER vehicles are control group vehicles and include 
vehicles of the same model years, similar body styles and price 
ranges to the TPMS vehicles, but which do not have TPMS.
---------------------------------------------------------------------------

    The 2,316 vehicles in the NCSA TPMS study were part of a complex 
random sample where vehicles had an unequal probability of selection 
from the population. Furthermore, data collection was terminated at an 
early stage due to the Court of Appeals' decision to vacate the TPMS 
standard, and as a result, the study did not reach the planned target 
sample size of 7,000 inspected vehicles. These factors could affect the 
results presented above because the sample may not be representative of 
the vehicle population. To address this concern, NCSA computed sample 
weights to adjust for the unequal probability of selection and to 
examine whether the results using the

[[Page 28893]]

raw (unweighted) data were affected by the sample selection. The 
analysis of weighted data found the average level of under-inflation to 
be 7% for vehicles equipped with indirect TPMSs and 6% for those 
equipped with direct TPMSs. The peer comparison vehicles without TPMSs 
were found to have levels of under-inflation of 9% and 10%, 
respectively. The differences between vehicles with TPMS and the peer 
vehicles are very similar to the results presented above, and thus the 
conclusions do not appear to be affected by the sample selection. The 
weighted differences, however, did not achieve statistical significance 
at conventional levels.
    In spite of the lack of statistical significance, we believe that 
the observed differences between vehicles with and without TPMS are 
real for at least two reasons. First, the finding is robust to both an 
analysis of the raw and weighted data. Second, the lack of statistical 
significance in the weighted analysis can be explained in part by the 
early termination of the study, which resulted in a smaller sample size 
and larger effects of the sample design on the estimated standard 
errors than would have occurred with the full study.
    The studies involving actual measurements of tire pressures suggest 
that drivers of TPMS-equipped vehicles engage in proper and regular 
tire maintenance and do not ordinarily wait for the TPMS warning before 
adding inflation pressure to their tires. Indeed, TPMS-equipped 
vehicles may, on average, have better maintained tire pressure. If 
these findings are correct, an expansion of TPMS fleet penetration 
could potentially bring similar inflation pressure improvements to all 
light vehicles, thereby positively impacting the target population 
identified in the earlier NCSA study.
    The RMA's assertion that TPMS would confuse or mislead consumers 
into believing that their tires are properly inflated whenever the TPMS 
warning is not illuminated is largely based on its telephone survey. 
Because we have concerns about that survey and because other studies 
suggest a different result, we do not believe the data support a 
conclusion that the TPMS rule is likely to result in a potentially 
dangerous decline in regular tire maintenance.

B. Tire Pressure Reserve To Offset Drops in Tire Pressure

    The RMA also argued that vehicle manufacturers should be required 
to provide a tire pressure reserve for their vehicles sufficient to 
offset drops in tire pressure that may occur before consumers are 
warned by the installed TPMS. The RMA argues that in order to prevent 
tire failures and protect consumers, vehicle manufacturers should be 
required to specify tires for their vehicles that can carry the 
vehicle's maximum load while operating at pressures that range from the 
placard pressure down to the TPMS warning threshold pressure.
    The RMA provided calculations of pressure reserve, based on maximum 
vehicle loads, for 100 sample vehicles from model years 1997 to 2003. 
The vehicles selected were from the following categories: sports car 
(11%), compact (14%), mid-size (20%), full-size (8%), luxury (19%), 
sport utility vehicle (SUV) (8%), van (15%), and pick-up truck (5 
percent). In summary, 72% of the RMA sample vehicles were passenger 
cars and 28% were light trucks.
    The RMA's tire pressure reserve calculations showed that 61% of the 
vehicles would have tire pressures below the pressures specified in the 
TRA tables for such loadings if (1) the vehicles in the study were 
equipped with a TPMS having a 25% below placard activation threshold, 
and if (2) the vehicles were operated with tire pressures just under 
the activation threshold, and if (3) the vehicles were fully loaded to 
their maximum weight rating. Alternatively, with the same assumptions 
as stated above, the RMA's calculations showed that 76% of the sampled 
vehicles could have pressure below the values listed in the TRA tables 
if their tires were under-inflated by 30% from the placard pressure. As 
a result, the RMA concluded that the placard pressure for many vehicles 
on the road today would be insufficient to carry the maximum load of 
the vehicle without over-deflecting the tires and causing tire damage, 
if the tires are operated at a level of under-inflation close to the 
TPMS activation threshold.
Agency Response
    The agency is not convinced that the calculations presented by the 
RMA reflect real-world conditions. The RMA's concern is premised on an 
assumption that operating below the values listed in the TRA tables is 
unsafe. We have been unable, however, to find any real world data to 
confirm that assumption. The RMA did not provide factual evidence 
showing that a pressure reserve requirement in itself would 
significantly reduce tire failures. And NHTSA's research, the details 
of which follow below, did not demonstrate a link between tire pressure 
reserve and tire failures. In addition, we are not aware of data, and 
the RMA has not provided any, showing that the RMA's sampled vehicles 
experience increased tire failure rates.
    The RMA data were developed assuming each of the sample vehicles is 
at its maximum loading condition. However, the data also indicate that 
many of these vehicles, when operating under normal load conditions 
(the most common situation), would be within the load-pressure 
operating range specified by the TRA tables, even when they are under-
inflated by 25% or 30% from placard pressure. In fact, NHTSA's data, 
which are based on a sample of 100 million vehicles, show that only 11% 
of the vehicles would have overloaded tires at normal loading condition 
when their tires are under-inflated 25% below placard pressure.\29\
---------------------------------------------------------------------------

    \29\ Docket No. NHTSA-2005-20967-2, p. 27.
---------------------------------------------------------------------------

    As defined earlier, the ``normal load'' on a vehicle is the typical 
load experienced during normal operation of the vehicle, which includes 
the vehicle curb weight, accessory weight, and the combined weight of 
the appropriate number of occupants. Moreover, there are no data 
showing that any vehicles have experienced higher tire failure rates 
due to the absence of a pressure reserve.
    The RMA's conclusion rests on industry-based TRA tables. However, 
the RMA has not provided any evidence to correlate tire inflation 
pressures at 25% below the values published in the TRA tables with real 
and significant safety consequences. Despite the fact that over a 
quarter of light vehicles on the road today having at least one tire 
under-inflated by at least 25%, as shown in the previously-discussed 
NCSA study, the data do not show large numbers of tire failures, as one 
might expect if in fact tire overload as defined by the TRA tables were 
the underlying cause of tire failure. It appears likely that the tire 
industry tables are conservative and may contain some built-in safety 
margin.
    In addition, an examination of the engineering formulae that serve 
as the basis for the TRA tables reveals that they are largely empirical 
and depend only on tire dimensions, as opposed to any material, design, 
construction, or loading factors. It is noteworthy that neither the RMA 
nor the TRA has provided NHTSA with technical or engineering data that 
would demonstrate a relationship between tire failures and load 
carrying capacity as defined in the TRA tables for pressures within the 
25% threshold of a TPMS.

[[Page 28894]]

NHTSA Data
    While RMA did not present data sufficient, in our view, to support 
granting its petition, the agency nonetheless decided to conduct 
independent research to determine whether a high tire reserve load 
correlates with a reduction in tire failures.
    The question of whether a pressure reserve requirement can reduce 
tire failures was first explored in a study conducted for NHTSA in the 
early 1980s. \30\ It examined whether there was a correlation between 
tire reserve load (which is equivalent to tire pressure reserve) and 
tire failure rates. The study analyzed a total of 1,760 tire failure 
records from MY 1974-1978 vehicles manufactured by General Motors, 
American Motors, Volkswagen, Datsun (currently known as Nissan), 
Toyota, Honda, Chrysler, and Ford. The tire reserve load values for 
groups of similar models produced in that period were collected from 
the vehicle manufacturers.
---------------------------------------------------------------------------

    \30\ The study, published in February 1981, was conducted by Chi 
Associates, Inc. This study can be found in NHTSA Docket No. 81-09-
NPRM-N01-001.
---------------------------------------------------------------------------

    After assigning each of the tire failure records to a particular 
vehicle group with a tire reserve load value, normalizing the data by 
the sales volumes for all the vehicles, and looking for a relationship 
between the frequency of tire failures and vehicles with different 
levels of tire reserve load, the study results were inconclusive. No 
correlation was found between tire failure rates and tire pressure 
reserve for vehicles manufactured by Ford, American Motors, and the 
import manufacturers, but there were increased tire failure rates as 
pressure reserve increased for Chrysler vehicles, and decreased tire 
failure rates as pressure reserve increased for General Motors 
vehicles.
    Based upon the results of the February 1981 study, NHTSA prepared 
an analysis titled, ``The Relationship Between Tire Reserve Load 
Percentages and Tire Failure Rates,''\31\ which concluded that there 
existed no consistent or reliable relationship between tire reserve 
load and tire failure rates. Accordingly, NHTSA decided at that time 
not to include a tire pressure reserve requirement in FMVSS No. 110.
---------------------------------------------------------------------------

    \31\ Docket No. 81-09-NPRM-N01-002.
---------------------------------------------------------------------------

    Nevertheless, because vehicles and tires have changed over the past 
25 years, NHTSA decided, in response to the RMA petition, to conduct an 
expanded and more comprehensive study to examine whether there now 
exists a relationship between tire pressure reserve and tire failure 
for light vehicles with a GVWR of 4,536 kilograms (10,000 pounds) or 
less.
    This more detailed study was designed to examine tire failure rates 
as a function of tire pressure reserve for the entire population of 
light vehicles sold in the United States from model years 1996 through 
2002.\32\ In January 2003, NHTSA issued Special Orders to vehicle and 
tire manufacturers and collected data on the total number of tire 
failure claims \33\ reported by consumers to those entities. The agency 
also collected data on vehicle production volumes and the pressure 
reserve values of every unique vehicle-tire group \34\ for those model 
years. A total of 24 vehicle manufacturers and 9 tire manufacturers 
reported 18,533 claims that occurred on 14,039 unique vehicle-tire 
groups, to the agency. The data represent just over 109 million 
vehicles that were produced during the model years examined under the 
study.
---------------------------------------------------------------------------

    \32\ The final report discussing the Special Order data and 
NHTSA's analysis can be found in the NHTSA docket, number NHTSA-
2005-20967-2. The report is titled: ``Data Submitted in Response to 
the Special Order on Tire Reserve Pressure.''
    \33\ The Special Orders defined ``tire failure'' as meaning the 
following: (1) Belt-to-belt separation, (2) belt edge separation, 
(3) sudden loss of inflation pressure, (4) separation of tread, 
sidewall, ply cord, inner liner, or bead, (5) chunking, (6) broken 
cords, (7) cracking, and (8) open splices. Tire failure was defined 
further as the manufacturer's ``opinion about the alleged failure 
mode and cause (from the list of 8 failure modes/causes listed under 
the definition of ``tire failure,'' specify all failure modes and 
causes that apply).''
    The Special Orders defined ``claim'' as meaning ``a written 
request or written demand for relief, including money or other 
compensation, assumption of expenditures, or equitable relief, 
related to a motor vehicle crash, accident, the failure of a 
component or system of a vehicle or an item of motor vehicle 
equipment, or a fire originating in or from a motor vehicle or a 
substance that leaked from a motor vehicle. Claim includes, but is 
not limited to, a demand in the absence of a lawsuit, a complaint 
initiating a lawsuit, an assertion or notice of litigation, a 
settlement, covenant not to sue or release of liability in the 
absence of a written demand, and a subrogation request. A claim 
exists regardless of any denial or refusal to pay it, and regardless 
of whether it has been settled or resolved in the manufacturer's 
favor. The existence of a claim may not be conditioned on the 
receipt of anything beyond the document(s) stating a claim. Claim 
does not include demands related to asbestos exposure, to emissions 
of volatile organic compounds from vehicle interiors, or to end-of-
life disposal of vehicles, parts or components of vehicles, 
equipment, or parts or components of equipment.''
    \34\ A ``vehicle-tire group'' means a category of vehicle 
possessing identical specifications for the following identifiers: 
vehicle make, vehicle model, model year, number of doors, number of 
drive wheels, gross-axle weight rating, make/model and size(s) of 
original equipment tires on each axle, and manufacturers recommended 
inflation pressure for tires on each axle.
---------------------------------------------------------------------------

    NHTSA examined separately P-metric tires (that are primarily 
intended for use on passenger cars but are often used on pick-up trucks 
and SUVs) and light truck (LT) tires. The data were also separated by 
one of four vehicle types (passenger car, SUV, van, and pick-up truck) 
and by axle (front vs. rear). The tire failure claim rate was lowest 
for passenger cars and vans equipped with P-metric tires. It was 
highest for pick-up trucks and SUVs equipped with LT tires. Claims were 
generally more common for tires on the rear axles of vehicles and for 
LT tires.
    Next, NHTSA calculated tire failure rates as a function of tire 
pressure reserve for 14 possible combinations of tire type, axle, and 
vehicle type. These were: P-metric tires on the front and rear axle of 
passenger cars (2 combinations); and P-metric and LT tires on the front 
and rear axles of pick-up trucks, SUVs, and vans (2x2x3 or 12 
additional combinations). Of these, there was sufficient information on 
10 combinations of vehicle type, axle, and tire type for analysis. 
These were P-metric tires on both axles of all four vehicle types, and 
LT tires on pick-up trucks.
    From there, the agency calculated tire failure rates for each of 
the 10 combinations and found only one statistically significant result 
suggesting an association between tire failure and tire pressure 
reserve (P-metric tires on the rear axle of passenger cars). However, 
one result is not sufficient to establish this relationship with any 
reasonable certainty. In a series of 10 tests, there is a high 
statistical probability of finding a result that appears to be 
significant, but is actually a matter of chance. In other words, even 
if there was no correlation between tire failure claims and tire 
pressure reserve, the agency would expect to find at least one result 
showing correlation (i.e., a false positive) about 40 percent of the 
time. Based on these results, the agency has concluded that comparisons 
of tire failure as a function of pressure reserve yield inconclusive 
results. These results are consistent with those of the 1981 study 
discussed above.\35\
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    \35\ We note that NHTSA has found this low incidence of actual 
tire failures, as revealed in the claims data in our study, to be 
repeated in laboratory testing as well. As noted in the June 5, 2002 
final rule for TPMS, the agency tested a variety of Standard Load P-
metric tires at 20 psi with 100 percent load at 75 mph for 90 
minutes on a dynamometer. None of the tires failed. (See 67 FR 
38704, 38726.)
---------------------------------------------------------------------------

    In order to confirm the results of the tire pressure reserve study, 
the agency also used a failure-time model with the Special Order data, 
which once again indicated conflicting results in terms of the impact 
of tire reserve load on the

[[Page 28895]]

probability of tire failure, none of which were statistically 
significant. Consequently, this model also did not establish a safety 
benefit associated with a tire pressure reserve.
    However, because this latter model produced a value that approached 
significance (p value = 0.06), we decided to use these results to 
develop a hypothetical estimate of the costs and benefits of a tire 
pressure reserve, for the moment assuming that an association had been 
demonstrated. The details of this analysis have been placed in the 
docket,\36\ but the following summarizes the key points.
---------------------------------------------------------------------------

    \36\ Docket No. NHTSA-2005-20967-3.
---------------------------------------------------------------------------

    Using this model, we produced an estimate of 2.15% fewer tire 
failures if all new vehicles were required to be fitted with tires that 
had, at a minimum, 8 psi of pressure reserve. If we assume that these 
changes would produce a proportionate reduction in tire-related deaths 
and injuries, then we can apply 2.15% to data from the Fatality 
Analysis Reporting System (FARS), the General Estimates System (GES), 
and the National Automotive Sampling Survey (NASS) to produce an 
estimate of safety benefits. Extrapolating from a previous NHTSA 
analysis,\37\ the agency estimates that the potential benefits would be 
prevention of 731 crashes (with roughly $2 million in property damage 
and travel delay savings), 4 fatalities, and 96 injuries in all cases 
involving blowouts or flat tires. However, this target population of 
all blowouts or flat tires is larger than could be impacted by tire 
reserve load, as many flat tires are caused by running over a hazardous 
object in the road and are not caused by factors influenced by tire 
reserve load. Thus, the unproven benefits listed above likely overstate 
the true potential benefits, although the magnitude of this 
overstatement is unclear.
---------------------------------------------------------------------------

    \37\ ``Final Regulatory Evaluation, FMVSS No. 139, New Pneumatic 
Tires for Light Vehicles,'' NHTSA, June 2003, p. S-2 (Docket No. 
NHTSA-2003-15400-2).
---------------------------------------------------------------------------

    In terms of costs, the RMA proposed that vehicle manufacturers 
could accommodate a tire pressure reserve requirement by simply raising 
the recommended tire inflation pressures or by specifying larger tires 
with more load carrying capacity for their vehicles. We do not believe 
this to be the case. We believe that a tire pressure reserve consistent 
with RMA's recommendation would have major technical and cost 
ramifications for the automotive industry and consumers, which could 
amount to approximately $132 million per year. For many vehicles, an 
increase in tire pressure of up to 8 psi may be necessary to meet the 
RMA's recommended tire pressure reserve, but increases of this 
magnitude could cause ride comfort to decrease considerably. In such 
cases, an increase in tire size would be needed, thereby triggering 
production changes and associated cost increases. Again, for a more 
complete discussion, please see the analysis of costs and benefits 
placed in the docket.\38\ Given that the agency's careful review of the 
data has found no demonstrable safety benefit from a tire pressure 
reserve requirement as would justify rulemaking, it is unlikely that 
imposition of these costs on consumers could withstand scrutiny under 
the rulemaking process.
---------------------------------------------------------------------------

    \38\ Docket No. NHTSA-2005-20967-3.
---------------------------------------------------------------------------

V. Conclusions

    The agency is not persuaded by the RMA's arguments that a tire 
pressure reserve requirement for light vehicles equipped with TPMSs is 
needed, for three reasons: (1) NHTSA does not agree with the RMA's 
claim that the TPMS standard will mislead consumers into believing that 
their tires are properly inflated whenever the TPMS warning telltale is 
not illuminated, because the petitioner has not provided compelling 
evidence that shows this to be the case; (2) the RMA did not provide 
data to show that tires on vehicles with little or no pressure reserve 
have a higher rate of failure in the field compared with vehicles 
having a high tire pressure reserve; and (3) the agency's independent 
studies have not shown a reliable or conclusive relationship between 
tire pressure reserve and tire failure claims in the field.
    For the reasons stated above, the agency is denying the petition. 
In accordance with 49 CFR Part 552, this concludes the agency's review 
of the petition.

    Authority: 49 U.S.C. 322, 30111, 30115, 30117, and 30162; 
delegation of authority at 49 CFR 1.50 and 501.8.

    Issued on: May 13, 2005.
Stephen R. Kratzke,
Associate Administrator for Rulemaking.
[FR Doc. 05-9989 Filed 5-18-05; 8:45 am]
BILLING CODE 4910-59-P