ac system GMC YUKON 2005 Owner's Manual
Page 440 of 530
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, 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
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 448 of 530
1. Open the spare tire lock cover on the bumper and
use the ignition key to remove the lock if your
vehicle is equipped with a hoist lock (J).
2. Assemble the wheel wrench (H) and the two jack
handle extensions (I) as shown.3. Insert the hoist end
(open end) (F) of the
extension through
the hole (G) in the
rear bumper.
Be sure the hoist end of the extension connects to
the hoist shaft (E). The ribbed square end of the
extension is used to lower the spare tire.
4. Turn the wheel wrench (H) counterclockwise to
lower the spare tire to the ground. Continue to
turn the wheel wrench until the spare tire can be
pulled out from under the vehicle.
If the spare tire does not lower to the ground, the
secondary latch is engaged causing the tire
not to lower. SeeSecondary Latch System on
page 5-87.
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Page 450 of 530
1. Remove the center cap by placing the chisel end of
the wheel wrench in the slot on the wheel and
gently prying the cap out.
If the wheel has bolt-on wheel covers, loosen the
plastic nut caps by turning the wheel wrench
in a counterclockwise direction. If needed, nish
loosening them by hand. The nut caps will not come
off. Using the at end of the wheel wrench, pry
along the edge of the cover until it comes off.2. Use the wheel wrench to loosen all the wheel nuts.
Turn the wheel wrench counterclockwise to loosen
the wheel nuts. Don’t remove the wheel nuts yet.
Notice:If your vehicle has QUADRASTEER™ and
you use a jack to raise the vehicle without
positioning it correctly, you could damage the
QUADRASTEER™ system. When raising your
vehicle on a jack, avoid contact with tie rods and
tie rod boots.
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