[Federal Register Volume 65, Number 101 (Wednesday, May 24, 2000)]
[Rules and Regulations]
[Pages 33481-33486]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-12873]
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DEPARTMENT OF TRANSPORTATION
National Highway Traffic Safety Administration
49 CFR Part 575
[Docket No. 00-7364]
RIN 2127-AG96
Consumer Information Regulations: Uniform Tire Quality Grading
Test Procedures
AGENCY: National Highway Traffic Safety Administration (NHTSA),
Department of Transportation (DOT).
ACTION: Final rule.
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SUMMARY: This final rule amends the treadwear testing procedures under
the Uniform Tire Quality Grading Standards (UTQGS). To ensure the
consistency of the treadwear grades from one year to the next, the
agency monitors the changing roughness of the test course, periodically
calculates a base course wear rate (BCWR), and uses it to adjust the
measured wear rates of tires driven over the course. To monitor the
test course, the agency uses special tires designated as course
monitoring tires (CMTs).
The agency is amending the UTQGS to change the computation of the
BCWR used in calculating the treadwear grade of passenger car tires.
These amendments establish a direct comparison of the wear rates of
CMTs used as the control standard with the wear rates of the candidate
tires, i.e., the tires being tested for the purposes of grading. This
direct comparison will result in more consistent treadwear ratings by
compensating for any changes or variations in CMT characteristics.
NHTSA will measure the wear rate of CMTs 4 times per year and use the
average wear rate from the last 4 quarterly CMT tests as a basis for
the BCWR. NHTSA is further requiring that CMTs used to determine wear
rate be not more than 1 year old at the commencement of the test and
that the CMTs used in the test must be used within 2 months after
removal from storage.
DATES: Effective date: The amendments in this final rule are effective
July 24, 2000.
Petitions for reconsideration of this final rule must be received
by NHTSA not later than July 10, 2000.
ADDRESSES: Petitions for reconsideration should be submitted to the
Administrator, National Highway Traffic Safety Administration, 400
Seventh Street, SW, Washington, DC 20590.
FOR FURTHER INFORMATION CONTACT:
For technical issues: Mr. Sanjay Patel, Safety Standards Engineer,
Office of Planning and Consumer Programs, Office of Safety Performance
Standards, National Highway Traffic Safety Administration, 400 Seventh
Street, SW, Washington, DC 20590; telephone (202) 366-0307.
For legal issues: Mr. Stephen P. Wood, Assistant Chief Counsel for
Rulemaking, National Highway Traffic Safety Administration, 400 Seventh
Street, SW, Washington, DC 20590; telephone (202) 366-2992.
SUPPLEMENTARY INFORMATION:
A. Background
1. Current Provisions.
Section 30123(e) of title 49, United States Code (U.S.C.) requires
the Secretary of Transportation to prescribe a uniform system for
grading motor vehicle tires to assist consumers in making informed
choices when purchasing tires. In response to that congressional
mandate, NHTSA established the Uniform Tire Quality Grading Standards
(UTQGS) in 49 CFR 575.104.
The UTQGS require tire manufacturers and tire brand name owners to
grade their tires with respect to the tires' relative performance with
respect to treadwear, traction, and temperature resistance. Treadwear
grades are shown by numbers, such as 100, 160, and 200, with the higher
numbers indicating greater treadwear performance. The traction grades
are indicated by AA, A, B, and C, with AA representing the highest
performance characteristics and C the lowest. The temperature
resistance grades are indicated by the letters A, B, and C, with A
representing the best performance and C indicating the minimum level of
performance necessary to comply with Federal motor vehicle safety
standards.
The UTQGS provide that treadwear grades are developed first by
running the tires being graded, called ``candidate tires,'' over a
selected 400-mile segment of public highway outside San Angelo, Texas.
After an 800-mile ``break-in'' run, the candidate tires are driven over
the test course for a total of 6,400 miles in test convoys composed of
4 passenger cars and/or light trucks. Each driver remains in the same
position within the convoy. The vehicles are regularly rotated among
the 4 positions in the convoy as are the positions of the tires on the
test vehicles so that each candidate tire gets equal time with each
driver, each vehicle, and each wheel position.
[[Page 33482]]
Special tires known as ``course monitoring tires'' (CMT) are used
as the control in grading candidate tires. CMTs are specially designed
and built to American Society for Testing and Materials (ASTM) standard
E1136 to have particularly narrow limits of variability.\1\ Until the
amendments to the UTQGS published in a final rule on September 9, 1996
(61 FR 4737), whenever the agency procured a new batch, or lot, of
CMTs, we established a new base course wear rate (BCWR) for that lot.
We established the BCWR, measured in mils per thousand miles, by
running tires from the new lot of CMTs over the 6,400-mile test course,
in the same manner as candidate tires, with tires from the previous
batch of CMTs. We determined a course severity adjustment factor (CSAF)
for the new CMTs by dividing the BCWR for the old CMTs by the average
wear rate of the old CMTs in the test. The wear rate of the new CMTs
was then multiplied by the CSAF to determine the adjusted wear rate
(AWR) of the new CMTs. That value then became the BCWR for the new
CMTs.
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\1\ The designation ``E1136'' refers to the standard
specification of materials and construction practices codified by
ASTM as suitable for control tires for scientific experimentation.
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Once the BCWR for the new CMTs was established, the new CMTs were
used to grade candidate tires. Upon completion of the 6,400-mile test,
the BCWR was divided by the average wear rate of the CMTs to determine
the CSAF for the candidate tires. That factor was then applied to the
wear rates of the candidate tires to obtain the AWR of the candidate
tires. That AWR was then extrapolated to the point of wearout
(considered to be \1/16\th inch of remaining tread depth). The
resultant value was then converted to the treadwear rating of the tire.
The BCWR was originally intended to provide a common baseline by
which to grade candidate tires by relating all new CMTs to the original
lot of CMTs. We noted, however, that the BCWRs of successive new lots
of CMTs steadily declined over the years. The trend has been that every
time a fresh CMT of the new lot was tested in the same convoy with an
old CMT, the fresh CMT consistently experienced a lower wear rate than
the old CMT. The first lot of CMTs that we procured in 1975 were
commercially-available Goodyear Custom Steelguards that yielded a BCWR
of 4.44. The lot of ASTM E-1136 CMTs that we procured in 1995, on the
other hand, produced a BCWR of 1.34. Table I shows the consistent
decline in wear rate for each new lot of CMTs.
CMT Wear Rate and Base Course Wear Rate Adjustment Factors
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Measured Adj. wear
Year Manufacturer Series wear rate CSAF rate BCWR
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1975................. Goodyear............... Batch 1 4.44 1.0 4.44 4.44
1979................. Goodyear............... Batch 1 4.08 1.09 4.44 ............
1979................. Goodyear............... Batch 2 3.82 1.09 4.16 4.16
1980................. Goodyear............... Batch 2 5.29 0.79 4.16 ............
1980................. Goodyear............... Batch 3 4.76 0.79 3.74 3.74
1984................. Goodyear............... Batch 3 4.22 0.89 3.74 ............
1984................. Uniroyal............... 4000 3.27 0.89 2.90 2.90
1987................. Uniroyal............... 4000 5.96 0.49 2.90 ............
1987................. Uniroyal............... 71000 4.56 0.49 2.22 2.22
1989................. Uniroyal............... 71000 5.01 0.44 2.22 ............
1989................. Uniroyal............... 91000 4.84 0.44 2.14 2.14
1991................. Uniroyal............... 91000 6.24 0.34 2.14 ............
1991................. ASTM E1136............. 010000 4.94 0.34 1.70 1.70
1991................. ASTM E1136............. 010000 6.96 0.24 1.70 ............
1992................. ASTM E1136............. 110000 6.65 0.24 1.62 1.62
1992................. ASTM E1136............. 110000 5.83 0.28 1.62 ............
1992................. ASTM E1136............. 210000 5.60 0.28 1.56 1.56
1993................. ASTM E1136............. 210000 7.21 0.22 1.56 ............
1993................. ASTM E1136............. 310000 6.80 0.22 1.47 1.47
1995................. ASTM E1136............. 310000 6.47 0.23 1.47 ............
1995................. ASTM E1136............. 410000 5.91 0.23 1.34 1.34
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In replacing CMTs from the original lot procured in 1975, we note
that the greatest difference in the AWR between nominally identical
CMTs of different ages was about 30 percent. This occurred in 1987 when
the old CMTs had been stored for about 3 years. The least difference in
the AWR between nominally identical CMTs of different ages was about 4
percent that occurred in the second 1992 replacement. At that time, the
old CMTs had been stored less than a year. Table I also shows that the
treadwear rate disadvantage of the aged CMTs at replacement varied
considerably from a linear relationship with age. This could suggest
that the rate may have been exacerbated by actual batch differences of
the commercial tires used as CMTs prior to 1991.
The significance of the decrease in the BCWR rate is that as the
BCWR decreased, the treadwear grades of candidate tires increased.
Consequently, the newer treadwear grades have increased to the point
that they are no longer a reliable indicator of actual treadwear
performance when compared to tires tested with higher BCWRs.
To correct this problem, we froze the BCWR at 1.34 mils in the
final rule of September 9, 1996 (61 FR 47437), believing that freezing
the BCWR at that figure would significantly reduce, if not eliminate,
any variation in the grading between lots. We also believed that the
use of ASTM E1136 tires that are produced with strict quality control
would also contribute to reduction of any lot-to-lot variations. We
stated, however, that we had requested the assistance of the ASTM F9
committee in devising a better treadwear test and that we would request
data in a future rulemaking on the effects of tire aging on treadwear
performance and storage procedures to reduce aging.
[[Page 33483]]
(2) Notice of Proposed Rulemaking
On June 5, 1998, we published a Notice of Proposed Rulemaking
(NPRM) proposing to revise the treadwear testing procedures of the
UTQGS to ensure the consistency of treadwear grades from one year to
the next. \2\ To achieve that result, we proposed to revise the
procedure for calculating the BCWR by directly comparing the wear rates
of CMTs with the wear rates of the candidate tires. Specifically, we
proposed to measure the wear rates of CMTs 4 times per year, then use
the average wear rate from the last 4 quarterly CMT tests as a basis
for the BCWR. We also proposed that CMTs used to determine the wear
rate be no more than 6 months old at the commencement of the test and
that the difference in production dates of the CMTs being tested be not
greater than 3 months. If CMTs being tested were more than 6 months
old, we proposed that the average wear rate be reduced by 10 percent.
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\2\ The NPRM originally called for a comment closing date of
August 4, 1998. At the request of the Rubber Manufacturers
Association, however, we extended the comment period until October
5, 1998 (63 FR 41538, August 4, 1998).
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B. Comments on the NPRM
We received 2 comments on the NPRM, one from the Rubber
Manufacturers Association (RMA), and the other from Uniroyal Goodrich
Tire Manufacturing (Uniroyal).
1. General
RMA opposed the proposals in the NPRM, stating that our action in
freezing the BCWR at 1.34 in the final rule of September 9, 1996 was
sufficient to solve the treadwear inflation problem. Uniroyal generally
supported the agency's intent in trying to ensure the consistency of
the treadwear grades from year to year, but believed that this can be
accomplished more efficiently than by the procedures that we proposed.
Both opposed our proposal to require that CMTs be not more than 6
months old when tested to determine the BCWR, arguing that that
requirement would increase the costs of production, shipping, and
storage for all manufacturers with no additional benefit for consumers.
Uniroyal, the sole current manufacturer of E-1136 tires, stated that
having to test CMTs that are 6-months old and within 3 months'
production dates of each other would mean that testers would specify
the most recent CMTs rather than take a chance on reducing their wear
rates by 10 percent. This would require that CMTs be produced on a
quarterly basis. Uniroyal stated that E-1136 tires are already produced
in extremely small quantities and that more frequent production would
be logistically impossible. RMA stated that the complexities associated
with coordination, production, shipping, storage, and testing of CMTs
and candidate tires within a 6-month period is not realistic. Both
commenters agreed that the cost and logistical problems of producing E-
1136 tires so frequently and in such small quantities would increase
the unit cost of such tires by a factor of 3 to 4 and could result in
less lot-to-lot consistency.
Both commenters supported a requirement that CMTs be tested within
1 year after production. RMA stated that if the proposals in the NPRM
are not withdrawn, it requested that no penalties be applied to tires
tested within 1 year of production. RMA argued that the aging
characteristics of CMTs and candidate tires would contribute to a
``leveling effect'' which, together with the logistical restrictions of
production, shipping, and storage, would minimize any difference in
tread life during the first year. RMA stated, however, that for CMTs
older than 1 year, any penalty should be no more than 5 percent.
Uniroyal recommended that E-1136 CMTs be utilized for testing up to 1
year after production, with no more than 3 months' difference in
production dates between the tires tested.
2. Additional Uniroyal Comments
a. Uniroyal suggested using a linear relationship to adjust for
aging of CMTs rather the ``step'' function that the agency proposed.
Uniroyal referred to NHTSA study DOT HS 808-701, Critical Evaluation of
UTQG Treadwear Testing & Methodology, which found an aging effect of
approximately 5 percent per year for cave-stored tires and about 10
percent for non-cave-stored tires. Thus, Uniroyal encouraged the
continued use of cave storage for CMTs.
Uniroyal recommended that tires used in NHTSA's tests be used as
soon as they are received from the cave and the BCWR calculated as
follows:
[GRAPHIC] [TIFF OMITTED] TR24MY00.003
Where:
ABCWR=Adjusted Base Course Wear Rate
BCWR=Base Course Wear Rate
TESTTWK-DOTWK CMT=Difference, in weeks, between date at
start of test and CMTDOT
AAF c=Age Adjustment Factor for cave-stored tires=0.05
The new adjusted base course wear rate will be obtained by using
average wear rate from the last 4 quarterly tests conducted by NHTSA.
(b) Since NHTSA showed in its study that CMTs that were not
continually cave-stored aged at twice the rate of those that were,
Uniroyal proposed the following calculation for the adjustment factor
if the production date of the CMT is older than that of the candidate
tire:
[GRAPHIC] [TIFF OMITTED] TR24MY00.004
Thus, the grade (P) would be computed as follows:
[[Page 33484]]
[GRAPHIC] [TIFF OMITTED] TR24MY00.005
Where:
ABCWR=Adjusted Base Course Wear Rate (from a. above)
DOTTWKTST-
DOTWKCMT=Difference, in weeks, between candidate tire
and CMT
AAF o=Age Adjustment Factor for tires stored at test site after
leaving cave=0.10
If the candidate tire is equal to or older than the CMT tire, no
adjustment is made.
c. NHTSA should measure the CMT wear rate at least 4 times per year
and include CMTs approximately one year old in their measurements. The
inclusion of older CMTs in these measurements would result in a long
term record of the aging effect and verify (or not) the approximately 5
percent per year age effect reported in DOT HS 808-701.
C. Discussion
For the past few years, NHTSA has been studying various ways to
arrest the consistent decline in the BCWR that we believe has been the
primary cause of the inflation that has plagued the treadwear grading
system almost from the beginning. That treadwear grade inflation was
the basis on which we froze the BCWR at 1.34 mils in the final rule of
September 9, 1996 (61 FR at 47441), which became effective March 9,
1998. The elapsed time since then has not given us sufficient data on
which to determine whether the freezing of the BCWR has had the desired
effect of arresting the treadwear grade inflation altogether, although
preliminary indications are that it has had a very positive effect on
the problem. In addition to contributing to the arrest of the treadwear
grade inflation, however, the procedures specified in this final rule
are intended to provide CMT replacement procedures that would be valid
in all circumstances. We could use these procedures, for example, if
ASTM changed its design specifications of the E-1136 tires; if E-1136
tires became unavailable and we were required to substitute other tires
for use as CMTs; or in the event of a significant change in the surface
of the test road course. Finally, these procedures will enable us to
test the assumption of batch uniformity of ASTM-specification tires.
NHTSA is persuaded by the comments of the RMA and Uniroyal that it
is not logistically feasible to produce E-1136 tires as frequently and
in such small lots as would be necessary to consistently provide CMTs
that are less than 6 months old. We have historically procured about
200 CMTs per year, retaining 12 for our own use and providing the
remainder to other testers. In making the CMT test runs 4 times per
year, we will now consume 64 CMTs per year, but the other testers are
expected to consume about the same number as before. Therefore, the
increase in the number of CMTs consumed per year is relatively small
and not enough to justify Uniroyal's having to make more production
runs of CMTs than before, with the additional logistical problems of
lot-to-lot consistency, storage, and shipping.
Because of Uniroyal's production and logistical constraints on the
manufacture of E-1136 tires, we have decided that the most practical
solution would be to require that CMTs used in establishing the BCWR be
less than 1 year old, instead of not more than 6-months old as we
proposed. Further, we will not require that the CMTs used in the
testing have production dates within 3 months of each other, nor will
we require the 10 percent adjustment for tires over the prescribed age
since this could create a demand for newer tires that would disrupt
Uniroyal's production schedule. We are, however, requiring that CMTs be
cave-stored until used \3\ and that, in addition to being not more than
1 year old, the CMTs must be used within 2 months after being removed
from cave storage. The 2-month requirement is intended to minimize any
degradation while in uncontrolled storage conditions. The aging of up
to 1 year in the cave could result in a degradation of up to 5 percent,
an amount that we have decided to accept under the circumstances as the
best compromise available within the economic constraints of the CMT
supply system.
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\3\ Uniroyal ships its E-1136 tires immediately after production
to a storage facility located in a cave in the Ozark mountains. This
facility has a constant temperature of about 60 deg.F. and is
remote from ozone-producing electrical equipment.
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Although the rate of treadwear degradation due to aging is not an
exact science, our experience has been that tires stored outside the
cave degrade at approximately 10 percent per year, while tires stored
under the controlled climatic conditions of the cave degrade at a
significantly lower rate, no more than a nominal 5 percent. The above
computations that Uniroyal suggested would compensate for that possible
5 percent aging degradation, if meticulous records were kept of the
amount of time each CMT spent in the cave and in uncontrolled storage
and if our estimate of the aging effect were accurate. We believe that
the proposed Uniroyal computation is too complicated in relation to the
small increase in accuracy. Therefore, for the sake of simplicity and,
as stated above, considering that the treadwear measurement is not a
precision test, we are willing to accept the possibility of tire
degradation of up to 5 percent, which might result in the slight
overgrading of candidate tires. Accordingly, we adhere to the formula
P = Projected mileage\*\BCWRn/402
that we proposed in the NPRM.
In summary, this final rule revises the procedure for measuring the
wear rate of CMTs by running them over the test course 4 times per
year, then using the average wear rate from the last 4 quarterly CMT
test runs as a basis for the BCWR. The CMTs used in the test runs must
be not more than 1 year old at the commencement of the test and must be
used within 2 months after being withdrawn from storage.
This final rule makes one additional change. NHTSA has been leasing
a warehouse to store the CMTs for sale to other testers. Given the
amendments made by this final rule, NHTSA need no longer store the CMTs
for the testers. They can purchase tires directly from the manufacturer
for less than what NHTSA was charging. Accordingly, we are amending
575.104(e)(1)(ii) to delete the sentence stating that CMTs are
available from NHTSA.
Rulemaking Analyses and Notices
a. Executive Order 12866 and DOT Regulatory Policies and Procedures
This document was not reviewed under Executive Order 12866,
Regulatory Planning and Review
NHTSA has analyzed the impact of this rulemaking action and has
determined that it is not ``significant'' under the DOT's regulatory
policies and
[[Page 33485]]
procedures. This action changes the calculation for determining the
base course wear rate of course monitoring tires which is, in turn,
used to determine the treadwear grade of candidate tires under the
Uniform Tire Quality Grading Standards. This action does not impose any
additional costs on motor vehicle or tire manufacturers, distributors,
or dealers. Instead, it permits tire manufacturers greater flexibility
in their testing programs and could result in slightly lower costs by
permitting them to procure course monitoring tires directly from the
manufacturer rather than through NHTSA, as has been the practice in the
past. Specifically, NHTSA has been leasing a warehouse to store the
CMTs for sale to other testers. We have charged them a markup on each
tire to cover our storage and handling expenses. Given the amendments
made by this final rule, NHTSA need no longer store the CMTs for the
testers. They can purchase tires directly from the manufacturer for
less than what NHTSA was charging, which also saves NHTSA the time,
trouble, and expense of storage and handling. We estimate that this
will save the tire companies approximately $24,000 per year.
Accordingly, because the cost savings are minimal, the agency did not
prepare a full regulatory evaluation.
b. Regulatory Flexibility Act
The agency has considered the effects of this rulemaking action
under the Regulatory Flexibility Act, 5 U.S.C. 601, et seq. I hereby
certify that this rulemaking action will not have a significant impact
on a substantial number of small entities.
The following is the agency's statement providing the factual basis
for the certification (5 U.S.C. 605(b)). The amendments proposed herein
will primarily affect manufacturers of passenger car tires. The Small
Business Administration (SBA) regulation at 13 CFR part 121 defines a
small business in part as a business entity ``which operates primarily
within the United States'' (13 CFR 121.105(a)).
SBA's size standards are organized according to Standard Industrial
Classification (SIC) codes. SIC code No. 3711, Motor Vehicles and
Passenger Car Bodies, has a small business size standard of 1,000 or
fewer employees. SIC code No. 3714, Motor Vehicle Parts and
Accessories, has a small business size standard of 750 or fewer
employees.
The amendments in this rulemaking action merely change the testing
procedure for and calculation of the treadwear grade under the Uniform
Tire Quality Grading Standards. The purpose of this new procedure is to
arrest the treadwear grade inflation that has been experienced over the
past several years. The amendments will make it necessary for NHTSA to
conduct additional testing to determine the base course wear rate from
which treadwear grades are calculated by tire manufacturers. The
amendments, however, will not impose any additional requirements or
burdens on tire manufacturers, most of which do not qualify as small
businesses under SBA guidelines. Thus, the new procedures will not
result in any increase in costs for tire manufacturers, small
businesses, or consumers. Accordingly, there will not be any
significant impact on small businesses, small organizations, or small
governmental units by the amendments in this final rule. Thus, the
agency has not prepared a final regulatory flexibility analysis. Annual
expenditures from this final rule will not exceed the $100 million
threshold.
c. Executive Order 13132 (Federalism)
The agency has analyzed this rulemaking in accordance with the
principles and criteria contained in Executive Order 13132 and has
determined that it does not have sufficient federalism implications to
warrant consultation with State and local officials or the preparation
of a federalism summary impact statement. The final rule has no
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.
d. National Environmental Policy Act
NHTSA has analyzed this rulemaking action for the purposes of the
National Environmental Policy Act and has determined that this
rulemaking action will not have any significant impact on the quality
of the human environment.
e. Paperwork Reduction Act
In accordance with the Paperwork Reduction Act of 1980, Pub.L. 96-
511, NHTSA states that there are no information collection requirements
associated with this rulemaking action.
f. Civil Justice Reform
The amendments made by this final rule will not have any
retroactive effect. Under 49 U.S.C. 30103(b), whenever a Federal motor
vehicle safety standard is in effect, a state or political subdivision
thereof may prescribe or continue in effect a standard applicable to
the same aspect of performance of a motor vehicle only if the standard
is identical to the Federal standard. However, the United States
government or a state or political subdivision of a state may prescribe
a standard for a motor vehicle or motor vehicle equipment obtained for
its own use that imposes a higher performance requirement than that
required by the Federal standard. Section 30161 of Title 49, U.S. Code
sets forth a procedure for judicial review of final rules establishing,
amending or revoking Federal motor vehicle safety standards. A petition
for reconsideration or other administrative proceedings is not required
before parties may file suit in court.
List of Subjects in 49 CFR Part 575
Consumer information, Labeling, Motor vehicle safety, Motor
vehicles, Rubber and rubber products, Tires.
In consideration of the foregoing, 49 CFR Part 575 is amended as
follows:
PART 575--CONSUMER INFORMATION REGULATIONS
1. The authority citation for Part 575 continues to read as
follows:
Authority: 49 U.S.C. 322, 30111, 30115, 30117, and 30166;
delegation of authority at 49 CFR 1.50.
2. Section 575.104 is amended by revising paragraph (e)(1)(ii),
paragraph (e)(2)(ix)(C), and paragraph (e)(2) (ix)(F), to read as
follows:
Sec. 575.104 Uniform tire quality grading standards.
* * * * *
(e) * * *
(1) * * *
(ii) Treadwear grades are evaluated by first measuring the
performance of a candidate tire on the government test course, and then
correcting the projected mileages obtained to account for environmental
variations on the basis of the performance of the course monitoring
tires run in the same convoy.
* * * * *
(2) * * *
(ix) * * *
(C) Determine the course severity adjustment factor by dividing the
base course wear rate for the course monitoring tires (see Note to this
paragraph) by the average wear rate for the four course monitoring
tires.
Note to paragraph (e)(2)(ix)(C): The base wear rate for the
course monitoring tires will be obtained by the government by
running ASTM E-1136 course monitoring tires for 6,400 miles over the
San Angelo, Texas, UTQGS test route 4 times per year, then using the
average wear rate from the last 4 quarterly CMT tests for the base
course wear rate calculation. Each new base course wear rate will be
filed in the DOT Docket
[[Page 33486]]
Management section. This value will be furnished to the tester by
the government at the time of the test. The course monitoring tires
used in a test convoy must be no more than one year old at the
commencement of the test and must be used within two months after
removal from storage.
* * * * *
(F) Compute the grade (P) of the NHTSA nominal treadwear value for
each candidate tire by using the following formula:
P = Projected mileage x base course wear raten/402
Where base course wear raten = new base course wear
rate, i.e., average treadwear of the last 4 quarterly course monitoring
tire tests conducted by NHTSA.
Round off the percentage to the nearest lower 20-point increment.
* * * * *
Issued on May 11, 2000.
Rosalyn G. Millman,
Acting Administrator.
[FR Doc. 00-12873 Filed 5-23-00; 8:45 am]
BILLING CODE 4910-59-P