Page 330 of 386

Buying New Tires
To ®nd out what kind and size of tires you need, look at
the Certi®cation/Tire label.
The tires installed on your vehicle when it was new had
a Tire Performance Criteria Speci®cation (TPC Spec)
number on each tire's sidewall. When you get new tires,
get ones with that same TPC Spec number. That way
your vehicle will continue to have tires that are designed
to give proper endurance, handling, speed rating,
traction, ride and other things during normal service on
your vehicle. If your tires have an all-season tread
design, the TPC number will be followed by an ªMSº
(for mud and snow).
If you ever replace your tires with those not having
a TPC Spec number, make sure they are the same
size, load range, speed rating and construction
type (bias, bias-belted or radial) as your original tires.{CAUTION:
Mixing tires could cause you to lose control
while driving. If you mix tires of different sizes
or types (radial and bias-belted tires) the
vehicle may not handle properly, and you
could have a crash. Using tires of different
sizes may also cause damage to your vehicle.
Be sure to use the same size and type tires on
all wheels.
{CAUTION:
If you use bias-ply tires on your vehicle, the
wheel rim ¯anges could develop cracks after
many miles of driving. A tire and/or wheel
could fail suddenly, causing a crash. Use only
radial-ply tires with the wheels on your vehicle.
5-60
Page 332 of 386

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 wheels on your vehicle were aligned and balanced
carefully at the factory to give you the longest tire life
and best overall performance.Scheduled wheel alignment and wheel balancing are
not needed. However, if you notice unusual tire wear or
your vehicle pulling one way or the other, the alignment
may need to be reset. If you notice your vehicle
vibrating when driving on a smooth road, your wheels
may need to be rebalanced.
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 if any of these conditions exist.
Your dealer 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
or wheel nuts, replace them only with new GM
original equipment parts. This way, you will be sure to
have the right wheel, wheel bolts and wheel nuts
for your vehicle.
5-62
Page 333 of 386

{CAUTION:
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.
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.
Whenever a wheel, wheel bolt or wheel nut is replaced
on a dual wheel setup, check the wheel nut torque
after 100, 1,000 and 6,000 miles (160, 1 600 and
10 000 km) of driving. For proper torque, see ªWheel Nut
Torqueº under
Capacities and Speci®cations on
page 5-97.
See
Changing a Flat Tire on page 5-65for more
information.
Used Replacement Wheels
{CAUTION:
Putting a used wheel on your vehicle is
dangerous. You can't know how it's been used
or how far it's 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
Notice:Use tire chains only where legal and only
when you must. Use chains that are the proper size
for your tires. Install them on the tires of the rear
axle. 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.
5-63
Page 334 of 386

If a Tire Goes Flat
It's unusual for a tire to ªblowoutº while you're driving,
especially if you maintain your tires properly. If air goes
out of a tire, it's much more likely to leak out slowly.
But if you should ever have a ªblowout,º here are a few
tips about what to expect and what to do:
If a front tire fails, the ¯at tire will create a drag that
pulls the vehicle toward that side. Take your foot off the
accelerator pedal and grip the steering wheel ®rmly.
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'd 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.{CAUTION:
Lifting a vehicle and getting under it to do
maintenance or repairs is dangerous without
the appropriate safety equipment and training.
The jack provided with your vehicle is
designed only for changing a ¯at tire. If it is
used for anything else, you or others could be
badly injured or killed if the vehicle slips off
the jack. Use the jack provided with your
vehicle only for changing a ¯at tire.
If a tire goes ¯at, the next part shows how to use your
jacking equipment to change a ¯at tire safely.
5-64
Page 335 of 386
Changing a Flat Tire
If a tire goes ¯at, avoid further tire and wheel damage
by driving slowly to a level place. Turn on your
hazard warning ¯ashers.
{CAUTION:
Changing a tire can cause an injury. The
vehicle can slip off the jack and roll over you
or other people. You and they could be badly
injured. Find a level place to change your tire.
To help prevent the vehicle from moving:
1. Set the parking brake ®rmly.
2. Put the shift lever in PARK (P).
3. Turn off the engine.
To be even more certain the vehicle won't
move, you can 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 of the vehicle, at the opposite end.The following steps will tell you how to use the jack and
change a tire.
5-65
Page 337 of 386
The tools you'll be using include the jack (A), jack
handle extension (B), jack handle (C), wheel wrench (D)
and the ratchet (E).
Your spare tire is stored underneath the rear of your
vehicle. You will use the wheel wrench (D) and the
ratchet (E) to lower the spare tire.
The ratchet has a DOWN side and an UP side.Attach the wheel wrench
and ratchet, with the
DOWN side facing you.
The wheel wrench
has a socket end and a
¯at chisel end.
Put the ¯at chisel end of the wheel wrench on an angle
through the hole between the body and the bumper.
Be sure the ¯at end connects into the hoist shaft.
5-67
Page 338 of 386
Turn the ratchet counterclockwise to lower the spare tire
to the ground. If the spare tire does not lower to the
ground, the secondary latch is engaged causing the tire
not to lower. See ªSecondary Latch Systemº later in
this section.When the tire has been lowered, pull the tire toward you
so you can reach the tire retainer and pull it up
through the wheel opening.
If you have a vehicle which was completed from a cab
and chassis, refer to the information from the body
supplier/installer.
The spare tire is a full-size tire, like the other tires on
your vehicle.
Notice:To help avoid vehicle damage, do not drive
the vehicle before the cable is restored.
5-68
Page 341 of 386

6. Place the jack under the vehicle, ahead of the rear
bumper. Position the center lift point of the jack
under the center of the spare tire and turn the
handle clockwise to raise the jack until it lifts the
secondary latch spring.
7. Keep raising the jack until the spare tire stops
moving upward and is held ®rmly in place, this
lets you know that the secondary latch has
released. The secondary latch has released and
the spare tire is balancing on the jack.8. Lower the jack by turning the ratchet
counterclockwise. Keep lowering the jack until the
spare tire slides off the jack or is hanging by
the cable.
9. Disconnect the jack handle from the jack and
carefully remove the jack. Use one hand to
push against the spare while ®rmly pulling the
jack out from under the spare tire with the
other hand.
If the spare tire is hanging from the cable, slide the
ratchet onto the wheel wrench and insert the
wheel wrench into the hoist shaft hole above the
bumper and turn the wheel wrench counterclockwise
to lower the spare the rest of the way. Be sure
the DOWN mark on the ratchet is facing you.
10. Tilt the retainer at the end of the cable and pull it
through the wheel opening. Pull the tire out from
under the vehicle.
11. If the cable is hanging under the vehicle, turn the
wheel wrench in the hoist shaft hole in the bumper
clockwise to raise the cable back up.
Have the hoist assembly inspected as soon as you can.
You will not be able to store a spare or ¯at tire using
the hoist assembly until it has been repaired or replaced.
To continue changing the ¯at tire, return to Step 4 of
ªRemoving the Flat Tire and Installing the Spare
Tireº later in this section.
5-71