And GMC ENVOY 2003 Owner's Manual

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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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.
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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.
{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.
See
Changing a Flat Tire on page 5-64for 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.
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Tire Chains
{CAUTION:
Don't use tire chains. There's 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 your
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
your vehicle and tire size combination and road
conditions. Follow that manufacturer's
instructions. To help avoid damage to your
vehicle, drive slowly, readjust or remove the
device if it's contacting your vehicle, and don't
spin your wheels. If you do ®nd traction devices
that will ®t, install them on the rear tires.
Accessory In¯ator
Your vehicle may be equipped with an air in¯ator
system. You can in¯ate things like basketballs and
bicycle tires. Also, you can use it to bring your tire
pressure up to the proper pressure. It is not designed to
in¯ate large objects which will require more than ®ve
minutes to in¯ate, such as an air mattress.
The air in¯ator is often
located in the rear
compartment on the
passenger's side of the
vehicle behind an
access cover.
To remove the cover, pull the two tabs on the cover and
pull it off.
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The air in¯ator kit may be located in the glove box. The
kit includes a 22 ft (6.7 m) hose with three nozzle
adapters.
To use the air in¯ator, attach the appropriate nozzle
adapter to the end of the hose if required. Then attach
that end of the hose to the object you wish to in¯ate.
Attach the other end of the hose to the outlet.
Press and release the switch to turn the air in¯ator on.
The indicator light will remain on when the in¯ator is
running.
The system has an internal clock to prevent overheating.
The system will allow about ®ve minutes of running
time, then the compressor will stop. The indicator light
will then begin to ¯ash. When the indicator is off,
the in¯ator can be started again by pressing the switch.
If the compressor is still hot, it may only run for a
short time before shutting off again.
Press and release the switch to turn the in¯ator off.
Place the in¯ator kit tools in the pouch and store
it properly. Remove the in¯ator hose from the outlet
during loading and unloading. Load leveling will
not function with the in¯ator hose attached to the in¯ator
outlet.To reinstall the cover, line up the tabs at the back of the
cover, put it in place and latch the tabs.
A continuous ¯ashing indicator light may also indicate a
malfunction in the air suspension system.
{CAUTION:
In¯ating something too much can make it
explode, and you or others could be injured.
Be sure to read the in¯ator instructions, and
in¯ate any object only to its recommended
pressure.
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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.
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.
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{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. If you have a four-wheel-drive vehicle,
be sure the transfer case is in a drive
gear ± not in NEUTRAL.
4. Turn off the engine.
5. Put the wheel 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

Removing the Spare Tire and Tools
The jacking equipment you will need is stored under the
rear seat in the Envoy or in the left rear quarter panel
storage compartment in the Envoy XL. To release
the jack from its holder, turn the knob on the jack
counterclockwise to lower the jack head. See
Rear Seat
Operation on page 1-6for more information. Envoy
Envoy XL
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The tools you'll be using include the wheel wrench (A),
tire blocks (B), extension(s) (socket end) (C), handle
(jack end) (D), and jack (E).
The following instructions explain how to remove the
spare tire mounted underneath your vehicle.
Notice:Never remove or restow a tire from/to a
storage position under the vehicle while the vehicle
is supported by a jack. Always tighten the tire
fully against the underside of the vehicle when
restowing.1. To remove the underbody-mounted spare, insert
the socket end of the extension on a 45É angle
downward into the hoist drive shaft hole. It is
exposed when the rear gate is open and is just
above the rear bumper. Be sure the socket end of
the extension connects into the hoist shaft.
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2. Turn the wheel wrench counterclockwise to lower
the spare tire. Keep turning 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 ªSecondary Latch Systemº later in
this section.
When the tire has been completely lowered, tilt the
retainer at the end of the cable and pull it through
the wheel opening. Pull the tire out from under
the vehicle.
Notice:To help avoid vehicle damage, do not drive
the vehicle before the cable is restored.
3. Put the spare tire near the ¯at tire.4. Use the chisel end of the wheel wrench to pry off
the center cap.
See ªRemoving the Flat Tire and Installing the Spare
Tireº later in this section to continue changing the
¯at tire.
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