Page 527 of 634
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 530 of 634
Tire Chains
{CAUTION:
If your vehicle has P265/65R18 or
P275/55R20 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.
CAUTION: (Continued)
CAUTION: (Continued)
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 has P265/70R17 size
tires, use tire chains only where legal and only
when you must. Use chains that are the proper
size for your vehicle’s tires. Install them on the
rear tires only.
Do not use chains on the front tires.
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 552 of 634
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. SeeIn ation - Tire
Pressure on page 515andLoading Your Vehicle on
page 407for information regarding proper tire
in ation and loading your vehicle. For instruction on
how to remove, install or store a spare tire, see
Removing the Flat Tire and Installing the Spare Tire
on page 537andStoring a Flat or Spare Tire and
Tools on page 547.
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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