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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.
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 specified
government test surfaces of asphalt and concrete.
A tire marked C may have poor traction
performance.
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
specified 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. It should
be noted that the temperature grade for this tire is
established for a tire that is properly inflated and
not overloaded. Excessive speed, underinflation,
or excessive loading, either separately or in
combination, can cause heat buildup and possible
tire failure.
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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.
If you need to replace any of your wheels, wheel bolts,
wheel nuts, or Tire Pressure Monitor System (TPMS)
sensors, replace them only with new GM original
equipment parts. This way, you will be sure to have the
right wheel, wheel bolts, wheel nuts, and TPMS sensors
for your vehicle.
{WARNING:
Using the wrong replacement wheels, wheel bolts,
or wheel nuts on your vehicle can be dangerous.
It could affect the braking and handling of your
vehicle, make your tires lose air and make you
lose control. You could have a collision in which
you or others could be injured. Always use the
correct wheel, wheel bolts, and wheel nuts for
replacement.
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Notice:The wrong wheel can also cause problems
with bearing life, brake cooling, speedometer or
odometer calibration, headlamp aim, bumper height,
vehicle ground clearance, and tire or tire chain
clearance to the body and chassis.
See Changing a Flat Tire
on page 7‑79for more
information.
Used Replacement Wheels
{WARNING:
Putting a used wheel on the vehicle is dangerous.
You cannot know how it has been used or how far
it has been driven. It could fail suddenly and
cause a crash. If you have to replace a wheel, use
a new GM original equipment wheel.
Tire Chains
{WARNING:
Do not use tire chains. 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 the
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 the
vehicle and tire size combination and road
conditions. Follow that manufacturer's
instructions. To help avoid damage to the vehicle,
drive slowly, re‐adjust or remove the device if it is
contacting the vehicle, and do not spin the
wheels. If you do find traction devices that will fit,
install them on the rear tires.
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If a Tire Goes Flat
It is unusual for a tire to blowout while you are driving,
especially if you maintain your vehicle's tires properly.
If air goes out of a tire, it is much more likely to leak out
slowly. But if you should ever have a blowout, here are
a few tips about what to expect and what to do:
If a front tire fails, the flat tire creates a drag that pulls
the vehicle toward that side. Take your foot off the
accelerator pedal and grip the steering wheel firmly.
Steer to maintain lane position, and then gently brake to
a stop well out of the traffic lane.
A rear blowout, particularly on a curve, acts much like a
skid and may require the same correction you would
use in a skid. In any rear blowout remove your foot from
the accelerator pedal. Get the vehicle under control by
steering the way you want the vehicle to go. It may be
very bumpy and noisy, but you can still steer. Gently
brake to a stop, well off the road if possible.{WARNING:
Lifting a vehicle and getting under it to do
maintenance or repairs is dangerous without the
appropriate safety equipment and training. If a
jack is provided with the vehicle, it is designed
only for changing a flat tire. If it is used for
anything else, you or others could be badly
injured or killed if the vehicle slips off the jack. If a
jack is provided with the vehicle, only use it for
changing a flat tire.
If a tire goes flat, the next part shows how to use the
jacking equipment to change a flat tire safely.
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Changing a Flat Tire
If a tire goes flat, avoid further tire and wheel damage
by driving slowly to a level place. Turn on the hazard
warning flashers. SeeHazard Warning Flashers
on
page 4‑3.
{WARNING:
Changing a tire can be dangerous. The vehicle
can slip off the jack and roll over or fall on you or
other people. You and they could be badly injured
or even killed. Find a level place to change your
tire. To help prevent the vehicle from moving:
1. Set the parking brake firmly.
2. Put the shift lever in P (Park).
3. Turn off the engine and do not restart while the vehicle is raised.
4. Do not allow passengers to remain in the vehicle.
To be even more certain the vehicle will not move,
you should put blocks at the front and rear of the
tire farthest away from the one being changed.
That would be the tire, on the other side, at the
opposite end of the vehicle. When the vehicle has a flat tire (B), use the following
example as a guide to assist you in the placement of
wheel blocks (A).
A. Wheel Block
B. Flat Tire
The following information explains how to use the jack
and change a tire.
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Removing the Spare Tire and Tools
The jack and the wheel blocks are located under a
cover near the passenger side rear seat.
Rear Seat (Passenger Side) Jack Cover
1. Remove the jack cover by turning the two wing nuts one-quarter turn counterclockwise and pulling
the jack cover off.
A. Wheel Blocks
B. Jack Knob
C. Wing Nut D. Retaining Hook
E. Jack
F. Mounting Bracket
2. Release the jack (E) from the mounting bracket (F) by turning the jack knob (B) on the jack
counterclockwise to release the jack from the
mounting bracket.
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3. Remove the wheel blocks (A) attachedto the jack (E) by turning the wing nut (C)
counterclockwise. Place the wheel blocks where
needed as indicated in previously in this section.
The tools for changing a flat tire are located in the
passenger's side top-box storage unit.
To remove the tools, do the following: 1. Open the top door on the passenger's side top-box storage unit. Use the ignition/door key to unlock it if
it is locked. See Top-Box Storage
on page 3‑76for more information.
2. Remove the black pouch from the storage box. You now have all of the tools you will need to lower
the spare tire and change a flat. To access the spare tire:
A. Spare Tire (Valve
Stem Pointed Down)
B. Hoist Assembly
C. Hoist Cable
D. Tire/Wheel Retainer E. Hoist Shaft
F. Hoist End of Extension Tool G. Hoist Shaft
Access Hole
H. Wheel Wrench I. Jack Handle Extension(s)
J. Spare Tire Lock
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1. Open the hoist shaft access cover on the bumperto access the spare tire lock (J).
2. To remove the spare tire lock, insert the ignition key, turn it clockwise and pull it straight out.
3. Assemble the two jack handle extensions (I) andwheel wrench (H) as shown.
4. Insert the open end ofthe extension (F)
through the hole in the
rear bumper (G) (hoist
shaft access hole).
Be sure the hoist end (F) of the extension connects
to the hoist shaft (E). The ribbed square end of the
extension is used to lower the spare tire.
Do not use the chiseled end of the wheel wrench.
5. Turn the wheel wrench 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. See Secondary Latch System
on page 7‑89for more information.
7-82