User Guide
I
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 wheels.
It’s all right to drive with your compact spare
(if
you have one). It was developed for use on
your vehicle.
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 lirnited-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 from the norm due to variations
in driving habits, service practices and differences
in
road characteristics and climate.
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