User Guide

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 wheels.
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,
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
.loo. The relative performance 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 -- 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
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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