wheel CHEVROLET ASTRO CARGO VAN 2004 2.G Service Manual

Tire Size
The following examples show the different parts of a
tire size.
(A) Passenger (P-Metric) Tire:The United States
version of a metric tire sizing system. The letter “P”
as the rst character in the tire size means a passenger
vehicle tire engineered to standards set by the U.S.
Tire and Rim Association.(B) Tire Width:The three-digit number indicates the
tire section width in millimeters from sidewall to sidewall.
(C) Aspect Ratio:A two-digit number that indicates
the tire height-to-width measurements. For example,
if the tire size aspect ratio is “75,” as shown in item “C”
of the illustration, it would mean that the tire’s sidewall
is 75% as high as it is wide.
(D) Construction Code:A letter code is used to
indicate the type of ply construction in the tire. The
letter “R” means radial ply construction; the letter “D”
means diagonal or bias ply construction; and the
letter “B” means belted-bias ply construction.
(E) Rim Diameter:Diameter of the wheel in inches.
(F) Service Description:The service description
indicates the load range and speed rating of a tire.
The load index can range from 1 to 279. Speed ratings
range from “A” to “Z”. The light truck tire size example
above shows dual or single tire congurations. Passenger (P-Metric) Tire
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(A) Light Truck (LT-Metric) Tire:The United States
version of a metric tire sizing system. The letter “LT”
as the rst two characters in the tire size means a light
truck tire engineered to standards set by the U. S.
Tire and Rim Association.
(B) Tire Width:The three-digit number indicates the
tire section width in millimeters from sidewall to sidewall.(C) Aspect Ratio:A two-digit number that indicates
the tire height-to-width measurements. For example,
if the tire size aspect ratio is “75,” as shown in item “C”
of the illustration, it would mean that the tire’s sidewall
is 75% as high as it is wide.
(D) Construction Code:A letter code is used to
indicate the type of ply construction in the tire. The letter
“R” means radial ply construction; the letter “D” means
diagonal or bias ply construction; and the letter “B”
means belted-bias ply construction.
(E) Rim Diameter:Diameter of the wheel in inches.
(F) Service Description:The service description
indicates the load range and speed rating of a tire.
The load index can range from 1 to 279. Speed ratings
range from “A” to “Z”. The light truck tire size example
above shows dual or single tire congurations. Light Truck (LT-Metric) Tire
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How to Check
Use a good quality pocket-type gage to check tire
pressure. You can’t tell if your tires are properly inated
simply by looking at them. Radial tires may look
properly inated even when they’re underinated.
Remove the valve cap from the tire valve stem. Press
the tire gage rmly onto the valve to get a pressure
measurement. If the cold tire ination pressure is low,
add air until you reach the recommended pressure
on the Certication/Tire label or the Tire and Loading
Information label.
If you overll the tire, release air by pushing on the
metal stem in the center of the tire valve. Recheck the
tire pressure with the tire gage.
Be sure to put the valve caps back on the valve stems.
They help prevent leaks by keeping out dirt and moisture.
Tire Inspection and Rotation
Tires should be rotated every 5,000 to 8,000 miles
(8 000 to 13 000 km).
Any time you notice unusual wear, rotate your tires as
soon as possible and check wheel alignment. Also
check for damaged tires or wheels. SeeWhen It Is Time
for New Tires on page 5-72andWheel Replacement
on page 5-75for more information.Make sure the spare tire is stored securely. Push,
pull, and then try to rotate or turn the tire. If it moves,
use the ratchet/wheel wrench to tighten the cable.
SeeChanging a Flat Tire on page 5-78.
The purpose of regular rotation is to achieve more
uniform wear for all tires on the vehicle. The rst rotation
is the most important. SeePart A: Scheduled
Maintenance Services on page 6-4.
When rotating your tires, always use the correct rotation
patterns shown here.
Don’t include the compact spare tire in your tire rotation.
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After the tires have been rotated, adjust the front
and rear ination pressures as shown on the
Certication/Tire label or Tire and Loading Information
label. SeeInation - Tire Pressure on page 5-70
andLoading Your Vehicle on page 4-29. Make
certain that all wheel nuts are properly tightened.
See “Wheel Nut Torque” underCapacities and
Specications on page 5-107.
{CAUTION:
Rust or dirt on a wheel, or on the parts to
which it is fastened, can make wheel nuts
become loose after a time. The wheel could
come off and cause an accident. When you
change a wheel, remove any rust or dirt from
places where the wheel attaches to the vehicle.
In an emergency, you can use a cloth or a
paper towel to do this; but be sure to use a
scraper or wire brush later, if you need to,
to get all the rust or dirt off. See “Changing
a Flat Tire” in the Index.
When It Is Time for New Tires
One way to tell when it’s
time for new tires is to
check the treadwear
indicators, which will
appear when your tires
have only 1/16 inch
(1.6 mm) or less of
tread remaining.
Some commercial truck
tires may not have
treadwear indicators.
You need a new tire if any of the following statements
are true:
You can see the indicators at three or more places
around the tire.
You can see cord or fabric showing through the
tire’s rubber.
The tread or sidewall is cracked, cut or snagged
deep enough to show cord or fabric.
The tire has a bump, bulge or split.
The tire has a puncture, cut or other damage that
can’t be repaired well because of the size or
location of the damage.
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Buying New Tires
To nd out what kind and size of tires you need, look
at the Certication/Tire label or the Tire and Loading
Information label. SeeLoading Your Vehicle on
page 4-29, for examples of the labels and where they
can be found on your vehicle.
The tires installed on your vehicle when it was new had
a Tire Performance Criteria Specication (TPC Spec)
number on each tire’s sidewall. When you get new
tires, GM recommends that you get tires 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 “MS” (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. It’s all right to drive with your
compact spare temporarily, it was developed
for use on your vehicle. SeeCompact Spare
Tire on page 5-90.
{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.
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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 specied 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 inated and
not overloaded. Excessive speed, underination, 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.
5-75

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.
SeeChanging a Flat Tire on page 5-78for 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 only SAE Class″S″type chains
that are the proper size for your tires. Install them
on the rear axle tires and 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.
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If a Tire Goes Flat
It’s unusual for a tire to “blowout” 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 “blowout,” 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.
5-77

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 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 rmly.
2. Put the shift lever in PARK (P).
3. Turn off the engine and do not restart
while the vehicle is raised.
4. Do not allow passengers to remain in
the vehicle.
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, at the opposite
end of the vehicle.
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2. Remove the wheel blocks by turning the top nut
counterclockwise. Remove the nut and washer,
then pull the wheel blocks off the bolt.
3. Push down on the bolt and remove the hooked
end from the slot. Slide the jack toward the front
of the vehicle and lift it from the mounting. Remove
the extension and the ratchet from the pouch.Your compact spare tire is stored underneath
the rear of your vehicle. You will use the ratchet
and extension to lower the compact spare tire.
5-80