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Uniform Tire Quality Grading
The following information relates to the system developed
by the United States National Highway Traffic Safety
Administration, which grades tires by treadwear, traction
and temperature performance. (This applies only to
vehicles sold in the United States.) The grades are molded
on the sidewalls of most passenger car tires. The Uniform
Tire Quality Grading system does not apply to deep tread,
A
CAUTION:
Mixing tires could cause you to lose control while
driving. If you mix tires of different sizes or types
(radial and bias-belted tires), the vehicle may not
handle properly, and you could have a crash.
Using tires of different sizes may also cause
damage to your vehicle. Be sure to use the same
size and type tires on all four wheels.
It's all right to drive with your compact spare,
though. It was developed for use on your vehicle.
winter-type snow tires, space-saver or temporary use spare
tires, tires with nominal rim diameters of 10 to 12 inches
(25 to 30 cm), or to some limited-production tires.
While the tires available on General Motors passenger
cars and light trucks may vary with respect to these
grades, they must also conform to Federal safety
requirements and additional General Motors Tire
Performance Criteria (TPC) standards.
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 a half (1 1/2) times as well
on the government course as a tire graded 100. The relative
performance of tires depends upon the actual conditions
of
their use, however, and may depart significantly fiom the
norm due to variations in driving habits, service practices
and differences in road characteristics and climate.
Traction
-
A, B, C
The traction grades, from highest to lowest, are A, B, and
C, and they represent the tire's ability to stop on wet
pavement as measured under controlled conditions on
k
specified government test surfaces of asphalt and concrete.
A tire marked C may have poor traction performance.
Warning: The traction grade assigned to this tire is based
on braking (straightahead) traction tests and does not
include cornering (turning) traction.
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