Uniform Tire Quality Grading
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.
.
If
you use bias-ply tires
on
your vehicle, the wheel
rim flanges could develop cracks after many
miles of driving.
A
tire and/or wheel could fail
suddenly, causing a crash. Use only radial-ply
tires with the wheels on
your
vehicle.
The following information relates
to
tne 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.
L.
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
1
50 would wear one and a half
(
1
1/2)
times
as
well on the government course
as
a tire
upon the actual conditions
of
their use, however, and
e
oraded
100.
The relative performance
of
tires depends
6-48
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