Page 495 of 596

Uniform Tire Quality Grading
Quality grades can be found where applicable on
the tire sidewall between tread shoulder and
maximum section width. For example:
Treadwear 200 Traction AA
Temperature A
The following information relates to the system
developed by the United States National Highway
Traffic Safety Administration (NHTSA), 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 (UTQG)
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 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 poor
traction 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.
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Page 498 of 596

Tire Chains
{CAUTION:
If your vehicle has dual wheels or P265/65R18,
P275/55R20 or LT265/70R17 size tires, do not
use tire chains. They can damage your vehicle
because there is not enough clearance. Tire
chains used on a vehicle without the proper
amount of clearance can cause damage to the
brakes, suspension, or other vehicle parts.
The area damaged by the tire chains could
cause you to lose control of your vehicle and
you or others may be injured in a crash.
Use another type of traction device only if its
manufacturer recommends it for use on your
vehicle and tire size combination and road
conditions. Follow that manufacturer’s
instructions. To help avoid damage to your
vehicle, drive slowly, readjust, or remove the
device if it is contacting your vehicle, and do
not spin your vehicle’s wheels.
If you do nd traction devices that will t,
install them on the rear tires.Notice:If your vehicle does not have dual wheels
and has a tire size other than P265/65R18,
P275/55R20 or LT265/70R17, use tire chains only
where legal and only when you must. Use chains
that are the proper size for your tires. Install them
on the tires of the rear axle. Do not use chains
on the tires of the front axle. Tighten them as
tightly as possible with the ends securely fastened.
Drive slowly and follow the chain manufacturer’s
instructions. If you can hear the chains contacting
your vehicle, stop and retighten them. If the
contact continues, slow down until it stops.
Driving too fast or spinning the wheels with
chains on will damage your vehicle.
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Page 519 of 596

3. Assemble the wheel blocks (B) and jack (G)
together with the wing nut (A) and retaining bolt (H).
4. Position the jack (G) in the mounting bracket (F).
Position the holes in the base of the jack (G) onto
the pin in the mounting bracket (F).
5. Return them to their original location in the vehicle.
For more information, refer toRemoving the Spare
Tire and Tools on page 5-95for more information.
Spare Tire
Your vehicle, when new, had a fully-in ated spare tire.
A spare tire may lose air over time, so check its
in ation pressure regularly. SeeInflation - Tire Pressure
on page 5-76andLoading Your Vehicle on page 4-36
for information regarding proper tire in ation and loading
your vehicle. For instruction on how to remove, install
or store a spare tire, seeRemoving the Flat Tire and
Installing the Spare Tire on page 5-100andStoring a
Flat or Spare Tire and Tools on page 5-110.
Notice:If your vehicle has four-wheel drive and
the different size spare tire is installed on your
vehicle, do not drive in four-wheel drive until you
can have your at tire repaired and/or replaced.You could damage your vehicle, and the repair costs
would not be covered by your warranty. Never use
four-wheel drive when the different size spare tire is
installed on your vehicle.
Your vehicle may have a different size spare tire than the
road tires originally installed on your vehicle. This spare
tire was developed for use on your vehicle, so it is all right
to drive on it. If your vehicle has four-wheel drive and the
different size spare tire is installed, keep the vehicle in
two-wheel drive.
After installing the spare tire on your vehicle, you should
stop as soon as possible and make sure the spare tire is
correctly in ated. Have the damaged or at road tire
repaired or replaced as soon as you can and installed
back onto your vehicle. This way, the spare tire will be
available in case you need it again.
Do not mix tires and wheels of different sizes, because
they will not t. Keep your spare tire and its wheel
together. If your vehicle has a spare tire that does not
match your vehicle’s original road tires and wheels in size
and type, do not include the spare in the tire rotation.
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