2002 GMC SIERRA Owner's Manual

6-44 Front Roof Marker Lamps
1. Remove the two screws
and lift off the lens.
The center roof marker lamp has six screws
to remove.
2. Turn the old bulb counterclockwise to remove it
from the socket.

6-45
3. Put a new bulb into the
socket and turn
clockwise until it locks
in place.
4. Reinstall the lens and tighten the screws.

6-46
Windshield Wiper Blade
Replacement
Windshield wiper blades should be inspected at least
twice a year for wear and cracking. See ªWiper Blade
Checkº in the Index for more information.
Replacement blades come in different types and are
removed in different ways. For proper type and length,
see ªNormal Maintenance Replacement Partsº in
the Index.
To replace the windshield wiper blade assembly, do
the following:
1. Lift the wiper arm and turn the blade until it is facing
away from the windshield.
2. Push the release lever and slide the wiper assembly
toward the driver's side of the vehicle.
3. Install a new blade by reversing Steps 1 and 2.

6-47
Tires
Your new vehicle comes with high-quality tires made by
a leading tire manufacturer. If you ever have questions
about your tire warranty and where to obtain service, see
your Warranty booklet for details.
CAUTION:
Poorly maintained and improperly used tires are
dangerous.

Overloading your tires can cause
overheating as a result of too much friction.
You could have an air
-out and a serious
accident. See ªLoading Your Vehicleº in
the Index.
CAUTION: (Continued)
CAUTION: (Continued)

Underinflated tires pose the same danger as
overloaded tires. The resulting accident
could cause serious injury. Check all tires
frequently to maintain the recommended
pressure. Tire pressure should be checked
when your tires are cold.

Overinflated tires are more likely to be
cut, punctured or broken by a sudden
impact
-- such as when you hit a pothole.
Keep tires at the recommended pressure.

Worn, old tires can cause accidents. If your
tread is badly worn, or if your tires have
been damaged, replace them.

6-48 Inflation -- Tire Pressure
The Certification/Tire label, which is on the rear edge of
the driver's door, shows the correct inflation pressures
for your tires when they're cold. ªColdº means your
vehicle has been sitting for at least three hours or driven
no more than 1 mile (1.6 km).
NOTICE:
Don't let anyone tell you that underinflation or
overinflation is all right. It's not. If your tires
don't have enough air (underinflation), you can
get the following:

Too much flexing

Too much heat

Tire overloading

Bad wear

Bad handling

Bad fuel economy
NOTICE: (Continued)
NOTICE: (Continued)
If your tires have too much air (overinflation),
you can get the following:

Unusual wear

Bad handling

Rough ride

Needless damage from road hazards
When to Check
Check your tires once a month or more. Also, check the
tire pressure of the spare tire.
How to Check
Use a good quality pocket
-type gage to check tire
pressure. You can't tell if your tires are properly inflated
simply by looking at them. Radial tires may look
properly inflated even when they're underinflated.
Be sure to put the valve caps back on the valve stems.
They help prevent leaks by keeping out dirt and
moisture.

6-49 Tire Inspection and Rotation
Tires should be rotated every 6,000 to 8,000 miles (10 000
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. See ªWhen It's
Time for New Tiresº and ªWheel Replacementº later in
this section for 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 wheel wrench/hoist shaft to
tighten the cable. See ªStoring a Flat or Spare Tire and
Toolsº in the Index.
The purpose of regular rotation is to achieve more uniform
wear for all tires on the vehicle. The first rotation is the
most important. See ªScheduled Maintenance Servicesº in
the Index for scheduled rotation intervals.
When rotating your tires, always use the correct rotation
pattern shown here. Don't include the spare tire in your
tire rotation.
After the tires have been rotated, adjust the front and
rear inflation pressures as shown on the
Certification/Tire label. Make certain that all wheel
nuts are properly tightened. See ªWheel Nut Torqueº in
the Index.
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
ªChanging a Flat Tireº in the Index.

6-50
When It's 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.
Buying New Tires
To find out what kind and size of tires you need, look at
the Certification/Tire label.
The tires installed on your vehicle when it was new had
a Tire Performance Criteria Specification (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.

6-51
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.
If your vehicle has 17 inch road tires (those
originally installed on your vehicle) it is all right
to drive with the 16 inch spare tire that came
with your vehicle. When new, your vehicle
included a spare tire and wheel assembly with the
same overall diameter as your vehicle's road tires
and wheels. Because this spare tire was developed
for use on your vehicle, it will not affect vehicle
handling or cause damage to your vehicle.
CAUTION:
If you use bias-ply tires on your vehicle, the
wheel rim flanges 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.