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 speci ed government test course.
For example, a tire graded 150 would wear one and
a half (1.5) 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 signi cantly 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 pavement as measured under controlled
conditions on speci ed government test surfaces of
asphalt and concrete. A tire marked C may have poortraction performance. Warning: 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.
Temperature – A, B, C
The temperature grades are A (the highest), B, and C,
representing the tire’s resistance to the generation
of heat and its ability to dissipate heat when tested
under controlled conditions on a speci ed indoor
laboratory test wheel. Sustained high temperature can
cause the material of the tire to degenerate 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.
Warning: The temperature grade for this tire is
established for a tire that is properly in ated and not
overloaded. Excessive speed, underin ation, or
excessive loading, either separately or in combination,
can cause heat buildup and possible tire failure.
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If a Tire Goes Flat
Your vehicle has no spare tire, no tire changing
equipment and no place to store a tire.
It’s unusual for a tire to “blow out” while you’re driving,
especially if you maintain your tires properly. See
Tires on page 5-51. If air goes out of a tire, it’s much
more likely to leak out slowly. But if you should
ever have a “blow out” here are a few tips about what to
expect and what to do:
If a front tire fails, the at tire will create a drag that
pulls the vehicle toward that side. Take your foot off the
accelerator pedal and grip the steering wheel rmly.
Steer to maintain lane position, and then gently brake to
a stop well out of the traffic lane.
A rear blow out, particularly on a curve, acts much like
a skid and may require the same correction you’d
use in a skid. In any rear blow out, remove your foot
from the accelerator pedal. Get the vehicle under control
by steering the way you want the vehicle to go. It may
be very bumpy and noisy, but you can still steer. Gently
brake to a stop, well off the road if possible.If a tire goes at, avoid further tire and wheel damage by
driving slowly to a level place and stopping. Then do this:
1. Turn on the hazard warning ashers.
2. Set the parking brake rmly.
3. Put the shift lever in PARK (P).
4. Turn off the engine.
5. Inspect the at tire.
If the tire has been separated from the wheel or has
damaged sidewalls or large tears that allow rapid
air loss, call a tire repair facility. SeeRoadside
Assistance Program on page 7-6.
If the at tire is due to a slow leak caused by a nail or
other similar road hazard, the tire in ator kit may
be used to repair the damaged tire temporarily. The kit
uses a liquid tire sealant to seal small punctures in
the tread area of the tire. The at tire is then in ated to
at least 26 psi (179 kPa) and driven to evenly distribute
the tire sealant. The tire pressure is checked after
driving for a maximum of 10 minutes to see if the
slow leak has been stopped. If the tire pressure is
19 psi (131 kPa) or more, in ate the tire up to the
standard operating pressure as shown on the tire and
loading information label found on center pillar near the
door latch or on the rear edge of the driver’s door.
SeeIn ation - Tire Pressure on page 5-58.
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