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 specified
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 significantly from the
norm due to variations in driving habits, service
practices, and differences in road characteristics
and climate.
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{CAUTION:
Incorrect or improperly tightened wheel nuts can
cause the wheel to come loose and even come off.
This could lead to a crash. If you have to replace
them, be sure to get new original equipment wheel
nuts. Stop somewhere as soon as you can and
have the nuts tightened with a torque wrench to the
proper torque specification. SeeCapacities and
Specifications on page 5-110for wheel nut torque
specification.
Notice:Improperly tightened wheel nuts can
lead to brake pulsation and rotor damage. To avoid
expensive brake repairs, evenly tighten the wheel
nuts in the proper sequence and to the proper torque
speci cation. SeeCapacities and Specifications on
page 5-110for the wheel nut torque speci cation.11. Use the wheel wrench to tighten the nuts firmly.
Turn the wheel wrench clockwise and in a
crisscross sequence as shown.
12. Put the wheel cover or the center cap and plastic
wheel nut caps back on. Remove any wheel
blocks.
Have a technician check the wheel nut tightness
of all wheels with a torque wrench after the first
100 miles (160 km) and then 1,000 miles (1600 km)
after that. Repeat this service whenever you have
a tire removed or serviced. SeeCapacities and
Specifications on page 5-110for more information.
5-90