1999 GMC ENVOY flat tire

yellowblue
5-18
Engine Fan Noise
This vehicle has a clutched engine cooling fan. When
the clutch is engaged, the fan spins faster to provide
more air to cool the engine. In most everyday driving
conditions, the clutch is not engaged. This improves fuel
economy and reduces fan noise. Under heavy vehicle
loading, trailer towing and/or high outside temperatures,
the fan speed increases when the clutch engages. So you
may hear an increase in fan noise. This is normal and
should not be mistaken as the transmission slipping or
making extra shifts. It is merely the cooling system
functioning properly. The fan will slow down when
additional cooling is not required and the
clutch disengages.
You may also hear this fan noise when you start the
engine. It will go away as the fan clutch disengages.
If a Tire Goes Flat
It's unusual for a tire to ªblow outº 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 flat tire will create a drag that
pulls the vehicle toward that side. Take your foot off the
accelerator pedal and grip the steering wheel firmly.
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.
If a tire goes flat, the next part shows how to use your
jacking equipment to change a flat tire safely.
ProCarManuals.com

yellowblue
5-19
Changing a Flat Tire
If a tire goes flat, avoid further tire and wheel damage
by driving slowly to a level place. Turn on your hazard
warning flashers.
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 firmly.
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.
ProCarManuals.com

yellowblue
5-20 Removing the Spare Tire and Tools
The jacking equipment you'll need is stored along the
driver's side inner rear quarter panel. Your vehicle is
also equipped with work gloves and a plastic ground
mat to assist in the changing of a flat tire.
To remove your jack cover,
pull up on the latches on the
cover. Remove the wheel
blocks, jack and
wheel wrench.
Your vehicle's spare tire is located underneath the rear
of your vehicle.
NOTICE:
Never remove or restow a tire from/to a stowage
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.
ProCarManuals.com

yellowblue
5-22
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.
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 properly stored.
Put the spare tire near the flat tire.The tools you'll be using include the jack (A) and wheel
wrench (B).
ProCarManuals.com

yellowblue
5-23
Position the chisel end of your wheel wrench in the
notch of the hub cap and pry off the hub cap.
Removing the Flat Tire and Installing the
Spare Tire
1. Using the wheel wrench, loosen all the wheel nuts.
Don't remove them yet.
2. Turn the jack handle clockwise to raise the jack
lift head.
3. Fit the jack into the appropriate hole nearest the
flat tire.
ProCarManuals.com

yellowblue
5-25
4. Raise the vehicle by turning the jack handle
clockwise. Raise the vehicle far enough off the
ground so there is enough room for the spare tire
to fit.
5. Remove all the wheel nuts and take off the flat tire.
6. Remove any rust or dirt
from the wheel bolts,
mounting surfaces and
spare wheel.
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.
ProCarManuals.com

yellowblue
5-28 Storing a Flat or Spare Tire and Tools
CAUTION:
Storing a jack, a tire or other equipment in the
passenger compartment of the vehicle could
cause injury. In a sudden stop or collision, loose
equipment could strike someone. Store all these
in the proper place.
NOTICE:
An aluminum wheel with a flat tire should always
be stored under the vehicle with the hoist.
However, storing it that way for an extended
period could damage the wheel. To avoid this,
have the wheel repaired as soon as possible.
Follow this diagram to store the
underbody
-mounted spare.
A. Retainer
B. Valve Stem
(Pointed Down)
C. Spare or Flat Tire
D. Spring
E. Wheel Wrench
F. Lower
G. Raise
H. Hoist Arm
1. Put the tire on the ground at the rear of the vehicle,
with the valve stem pointed down and to the rear.
2. Pull the retainer through the wheel.
3. Put the chisel end of the wheel wrench, on an angle,
through the hole in the rear bumper and into the hoist
shaft. Turn the wheel wrench clockwise until the tire
is raised against the underside of the vehicle.
You will hear two ªclicksº when the tire is secure,
but pull on the tire to make sure.
ProCarManuals.com

yellowblue
6-37
6. Put the blade assembly pivot in the wiper arm hook.
Pull up until the pivot locking tab locks in the
hook slot.
7. Carefully lower the wiper arm and blade assembly
onto the windshield.
Backglass Wiper Blade Replacement
See ªWindshield Wiper Blade Replacementº in this
section for instructions on how to change the backglass
wiper blade. The backglass wiper blade will not lock in
a vertical position like the windshield wiper blade, so
care should be used when pulling it away from
the vehicle.
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 GMC 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.

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.
ProCarManuals.com