1999 GMC SONOMA inflation pressure

4-40
Dust or dirt can enter the back of the transmission
through the opening created by removing the propeller
shaft if proper protection is not provided. Also, check
the transmission fluid level before driving the vehicle.
When towing your vehicle, turn the ignition to OFF.
To prevent your battery from draining while towing,
remove the RDO BATT fuse from the instrument panel
fuse block. Be sure to replace the fuse when you reach
your destination. See ªFuses and Circuit Breakersº in
the Index.
Be sure to use the proper towing equipment designed for
recreational vehicle towing. Follow the instructions for
the towing equipment.Loading Your Vehicle
The Certification/Tire label is found on the driver's door
edge, above the door latch. The label shows the size of
your original tires and the inflation pressures needed to
obtain the gross weight capacity of your vehicle. This is
called the Gross Vehicle Weight Rating (GVWR). The
GVWR includes the weight of the vehicle, all occupants,
fuel, cargo and trailer tongue weight, if pulling a trailer.

5-30
A. Bolt
B. Cover (Standard Cab)
C. Cover (Extended Cab)
Compact Spare Tire (If Equipped)
Although the compact spare tire was fully inflated
when your vehicle was new, it can lose air after a time.
Check the inflation pressure regularly. It should be
60 psi (420 kPa).
After installing the compact spare on your vehicle, you
should stop as soon as possible and make sure your spare
tire is correctly inflated. The compact spare is made to
perform well at speeds up to 65 mph (105 km/h) for
distances up to 3,000 miles (5 000 km), so you can finish
your trip and have your full
-size tire repaired or replaced
where you want. Of course, it's best to replace your spare
with a full
-size tire as soon as you can. Your spare will last
longer and be in good shape in case you need it again.
NOTICE:
When the compact spare is installed, don't take
your vehicle through an automatic car wash with
guide rails. The compact spare can get caught on
the rails. That can damage the tire and wheel,
and maybe other parts of your vehicle.

6-46 Inflation -- Tire Pressure
The Certification/Tire label, which is on the driver's
door door edge, above the door latch, 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.
If you have a compact spare tire, it should be at
60 psi (420 kPa).
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.

6-47 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 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 one of the correct
rotation patterns shown here.
If your vehicle has a compact spare tire, don't include it
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.

7-42
Part B: Owner Checks and Services
Listed in this part are owner checks and services which
should be performed at the intervals specified to help
ensure the safety, dependability and emission control
performance of your vehicle.
Be sure any necessary repairs are completed at once.
Whenever any fluids or lubricants are added to your
vehicle, make sure they are the proper ones, as shown in
Part D.
At Each Fuel Fill
It is important for you or a service station attendant to
perform these underhood checks at each fuel fill.
Engine Oil Level Check
Check the engine oil level and add the proper oil if
necessary. See ªEngine Oilº in the Index for
further details.Engine Coolant Level Check
Check the engine coolant level and add DEX
-COOL

coolant mixture if necessary. See ªEngine Coolantº in
the Index for further details.
Windshield Washer Fluid Level Check
Check the windshield washer fluid level in the
windshield washer tank and add the proper fluid if
necessary. See ªWindshield Washer Fluidº in the Index
for further details.
At Least Once a Month
Tire Inflation Check
Make sure tires are inflated to the correct pressures.
Don't forget to check your spare tire. See ªTiresº in the
Index for further details.
Cassette Deck Service
Clean cassette deck. Cleaning should be done every
50 hours of tape play. See ªAudio Systemsº in the Index
for further details.

7-43 At Least Twice a Year
Restraint System Check
Make sure the safety belt reminder light and all your
belts, buckles, latch plates, retractors and anchorages are
working properly. Look for any other loose or damaged
safety belt system parts. If you see anything that might
keep a safety belt system from doing its job, have it
repaired. Have any torn or frayed safety belts replaced.
Also look for any opened or broken air bag coverings,
and have them repaired or replaced. (The air bag system
does not need regular maintenance.)
Wiper Blade Check
Inspect wiper blades for wear or cracking. Replace blade
inserts that appear worn or damaged or that streak or
miss areas of the windshield. Also see ªWiper Blades,
Cleaningº in the Index.Spare Tire Check
At least twice a year, after the monthly inflation check
of the spare tire determines that the spare is inflated to
the correct tire inflation pressure, make sure that the
spare tire is stored securely. Push, pull, and then try to
rotate or turn the tire. If it moves, use the wheel wrench
to tighten the cable. See ªStoring the Spare Tire and
Toolsº in the Index.
Weatherstrip Lubrication
Silicone grease on weatherstrips will make them last
longer, seal better, and not stick or squeak. Apply
silicone grease with a clean cloth. During very cold,
damp weather more frequent application may be
required. (See ªRecommended Fluids and Lubricantsº in
the Index.)
Manual Transmission Check
Check the transmission fluid level; add if needed. See
ªManual Transmission Fluidº in the Index. Check for
leaks. A fluid leak is the only reason for fluid loss. Have
the system inspected and repaired if needed.