1999 GMC C-SERIES spare tire

yellowblue
5-35

If the wheel looks normal, see if the wheel has side
rings and a lock ring around the wheel rim. If so,
they must be seated properly. You can compare with
another wheel on the vehicle as you check for this.
For dual wheels, you have to look between the tires
to make this check. You may not be able to tell
if the side rings or lock rings are seated properly
by looking. If you can't be sure, stop and get
expert help.
CAUTION:
If you work on a pressurized tire mounted on a
damaged wheel, the assembly can expand with
explosive force without warning. You and others
nearby can be badly injured. Don't work around
a tire that has air under pressure in it when its
lock ring or side ring might not be
properly seated.
CAUTION:
Rust or dirt on the wheel, or on the parts to
which it is fastened, can make the 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 the 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.

If the lock ring and side rings seem to be seated
properly (or if the wheel doesn't have these), let the
air out of the tire. You can do this by taking out the
valve core.

If the flat or damaged tire is one of a dual set, let the
air out of both tires of the dual before you take off
the damaged tire and rim assembly.

If you have the correct equipment, put on the spare
wheel and tire assembly.
ProCarManuals.com

yellowblue
6-49 Inflation -- Tire Pressure
The Certification/Tire label, which is on 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.
ProCarManuals.com

yellowblue
6-50 Rims and Wheels
Rims and wheels are stamped with a maximum load and
cold inflation rating. Be sure you don't exceed these limits.
Dual Tire Operation
When the vehicle is new, or whenever a wheel, wheel
bolt or wheel nut is replaced, check the wheel nut torque
as indicated:
If your vehicle has stud piloted or hub piloted wheels,
tighten the wheel stud nuts to the specified torque values
at 100 miles (160 km), 500 miles (800 km) and
1,000 miles (1 600 km) and then every 1,000 miles
(1 600 km) thereafter.
For proper torque, see ªWheel Nut Torqueº in the Index.
The outer tire on a dual wheel setup generally wears
faster than the inner tire. Your tires will wear more
evenly and last longer if you rotate the tires periodically.
If you're going to be doing a lot of driving on
high
-crown roads, you can reduce tire wear by adding
5 psi (35 kPa) to the tire pressure in the outer tires. Be
sure to return to the recommended pressures when no
longer driving under those conditions. See ªChanging a
Flat Tireº in the Index for more information.
CAUTION:
If you operate your vehicle with a tire that is
badly underinflated, the tire can overheat. An
overheated tire can lose air suddenly or catch
fire. You or others could be injured. Be sure
all tires (including the spare, if any) are
properly inflated.
ProCarManuals.com