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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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.
Wheel Alignment and Tire Balance
The tires and wheels on your vehicle were aligned
and balanced carefully at the factory to give you the
longest tire life and best overall performance.
Adjustments to wheel alignment and tire balancing will
not be necessary on a regular basis. However, if
you notice unusual tire wear or your vehicle pulling to
one side or the other, the alignment might need to
be checked. If you notice your vehicle vibrating when
driving on a smooth road, the tires and wheels
might need to be rebalanced. See your dealer/retailer
for proper diagnosis.
Wheel Replacement
Replace any wheel that is bent, cracked, or badly rusted
or corroded. If wheel nuts keep coming loose, the wheel,
wheel bolts, and wheel nuts should be replaced. If the
wheel leaks air, replace it (except some aluminum
wheels, which can sometimes be repaired). See your
dealer/retailer if any of these conditions exist.
Your dealer/retailer will know the kind of wheel you need.
Each new wheel should have the same load-carrying
capacity, diameter, width, offset, and be mounted
the same way as the one it replaces.
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{CAUTION:
When the TIRE FLAT MAX SPD 55, REDUCED
HNDLG message is displayed on the Driver
Information Center, your vehicle’s handling
capabilities will be reduced during severe
maneuvers. If you drive too fast, you could
lose control of your vehicle. You or others
could be injured. Don’t drive over 55 mph
(90 km/h) when the TIRE FLAT MAX SPD 55,
REDUCED HNDLG message is displayed.
Drive cautiously and check your tire pressures
as soon as you can.
If the TPM system detects a tire pressure below
5 psi (34 kPa), the TIRE FLAT MAX SPD 55, REDUCED
HNDLG warning message is displayed on the Driver
Information Center (DIC). SeeDIC Operation and
Displays on page 3-60andDIC Warnings and Messages
on page 3-63for information and details about the
DIC operation and displays.
{CAUTION:
Special tools and procedures are required to
service a run- at tire. If these special tools and
procedures are not used you or others could
be injured and your vehicle could be damaged.
Always be sure the proper tools and
procedures, as described in the service
manual, are used.
Notice:Using liquid sealants can damage the tire
valves and tire pressure monitor sensors in your
vehicle’s run- at tires. This damage would not
be covered by warranty. Do not use liquid sealants
in your vehicle’s run- at tires.
To order a service manual, seeService Publications
Ordering Information on page 8-16.
If a tire goes at, the stability control system will turn
on automatically even if it was disabled by the driver.
When a at tire condition exists the StabiliTrak
®system
cannot be turned off. SeeStabiliTrak®System on
page 5-8.
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