Vehicle care and maintenance
7-27
7
Treadwear, Traction and Temperature GradesTr e a d w e a r
The treadwear grade is a comparative rating based on the
wear rate of the tire when tested under controlled conditions
on a specified government test course. For example, a tire
graded 150 would wear one and one-half (1
1/2) times as
well on the government course as a tire graded 100. The rel-
ative performance of tires depends upon the actual condi-
tions of their use, however, and may depart significantly
from the norm due to variations in driving habits, service
practices and differences in road characteristics and climate.
Traction
The traction grades, from highest to lowest, are AA, A, B
and C. Those grades represent the tire’s ability to stop on
wet pavement as measured under controlled conditions on
specified government test surfaces of asphalt and concrete.
A tire marked C may have poor traction performance.
Te m p e r a t u r e
The temperature grades are A (the highest), B and C, repre-
senting the tire’s resistance to the generation of heat and its
ability to dissipate heat when tested under controlled condi-
tions on a specified indoor laboratory test wheel. Sustained
high temperature can cause the material of the tire to degen-
erate and reduce tire life, and excessive temperature can
lead to sudden tire failure. The grade C corresponds to a
level of performance which all passenger car tires must meet
under the Federal Motor Vehicle Safety Standard No. 109.
Grades B and A represent higher levels of performance on
the laboratory test wheel than the minimum required by law.
Tire inflation pressures
N00939300815
Proper tire inflation pressure is essential for the safe and satis-
factory operation of your vehicle. The wrong tire pressure will
cause problems in three major areas:
Safety
Too little pressure increases flexing in the tire and can
cause tire failure. Too much pressure can cause a tire to
lose its ability to cushion shock. Objects on the road and
potholes could then cause tire damage that may result in
tire failure.
Economy
The wrong tire pressure can cause uneven wear patterns in
the tire tread. These abnormal wear patterns will reduce
the tread life, and the tire will have to be replaced sooner.
Too little pressure also makes it harder for the tire to roll,
and this uses up more fuel.
Ride comfort and vehicle stability
The superior riding experience built into your vehicle
partly depends on the correct tire pressure. Too much
pressure gives an uncomfortable and jarring ride. Too lit-
tle pressure feels as if your vehicle is slow to respond.
Unequal tire pressures can make steering your vehicle
uneven and unpredictable.
The tire pressure for your vehicle under normal driving condi-
tions is listed on the placard attached to the driver’s door sill.
(Refer to “Tire and loading information placard” on page 9-4.)
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8-2 Customer assistance/Reporting Safety Defects
8Consumer information (For vehicles sold in
U.S.A.)
N01047100171
This information is provided in compliance with the require-
ments of the National Highway Traffic Safety Administration,
Department of Transportation. It provides the purchasers
and/or prospective purchasers with information on reporting
safety defects. Uniform tire quality gradingDOT quality grades - All passenger vehicle tires must conform
to Federal Safety Requirements in addition to these grades. The
specific grade rating in each grade category is shown on the
side wall of the tires on your vehicle. Treadwear The treadwear grade is a comparative rating based on the wear
rate of the tire when tested under controlled conditions on a
specified government test course. For example, a tire graded
150 would wear one and one-half (1
1/2) times as well on the
government course as a tire graded 100. The relative perfor-
mance of tires depends upon the actual conditions of their use,
however, and may depart significantly from the norm due to
variations in driving habits, service practices and differences in
road characteristics and climate.
Traction AA, A, B, C The traction grades, from highest to lowest, are AA, A, B and
C. Those grades represent the tire’s ability to stop on wet pave-
ment as measured under controlled conditions on specified
government test surfaces of asphalt and concrete. A tire
marked C may have poor traction performance.
Temperature A, B, CThe temperature grades are A (the highest), B and C, represent-
ing the tire’s resistance to the generation of heat and its ability
to dissipate heat when tested under controlled conditions on a
specified indoor laboratory test wheel. Sustained high tempera-
ture can cause the material of the tire to degenerate and reduce
tire life, and excessive temperature can lead to sudden tire fail-
ure. The grade C corresponds to a level of performance which
all passenger car tires must meet under the Federal Motor Vehi-
cle Safety Standard No. 109. Grades B and A represent higher
levels of performance on the laboratory test wheel than the
minimum required by law.
WA R N I N G
!The traction grade assigned to this tire is based on
straight-ahead braking traction tests, and does not
include acceleration, cornering, hydroplaning, or
peak traction characteristics.
WA R N I N G
!The temperature grade for this tire is established for
a tire that is properly inflated and not overloaded.
Excessive speed, underinflation, or excessive load-
ing, either separately or in combination, can cause
heat buildup and possible tire failure.
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