tires GMC C-SERIES 1999 Owner's Manual

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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.
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6-51 When It's Time for New Tires
Replace your tires when the tread depth is down to
1/8 of an inch (3.2 mm) for the front tires, or 1/16 of
an inch (1.6 mm) for a rear tire. Also, you need a new
tire if:

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.
CAUTION:
Mixing tires could cause you to lose control while
driving. If you mix tires of different types
-- like
radial and bias
-belted tires -- the vehicle may not
handle properly, and you could have a crash.
Be sure to use the same type of tires all around.
When you replace tires, make sure they are the same
size, load range, speed rating and construction type
(bias, bias
-belted or radial) as your original tires.
Wheel Alignment and Tire Balance
The wheels on your vehicle were aligned at the
factory to give you the longest tire life and best
overall performance.
Proper front wheel alignment must be maintained in
order to ensure efficient steering, good directional
stability, and prevent abnormal tire wear. If you notice
unusual tire wear or your vehicle is 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 balanced.
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6-57
CAUTION:
Rust or dirt on a 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 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.
How Often to Check
Wheel tightness is so important you should have a
technician check nut tightness on all wheels with a
torque wrench every 1,000 miles (1 600 km).
When your vehicle is new or when a wheel or fastener is
new you should have a technician tighten the wheel
stud and rim clamp nuts, with a torque wrench, at
100, 500 and 1,000 miles (160, 800 and 1 600 km).
The reason for this is that the clamping system has to
seat before the fasteners will stay tightened.
Wheel Replacement
Replace any wheel that is bent, cracked or badly rusted.
If wheel nuts keep coming loose, replace the wheel.
If the wheel leaks air, replace it.
Your dealer will know the kind of wheel you need.
CAUTION:
A leaking wheel could fail without warning. A
wheel designed for tubeless tires could be leaking
because it is damaged. Don't use an inner tube or
some other thing to try to stop the leaking. Get a
new wheel of the proper type.
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6-58
CAUTION:
Without the correct wheel, you may not be able
to stop properly, and you could have other
problems like a tire air
-out. You could have a
collision. If you don't go to your dealer to get a
new wheel, be sure you get the correct one. Each
new wheel should match the original wheel in
load
-carrying capacity, inflation pressure
capacity, diameter, width, offset and mounting
configuration.
Using wheels and tires with higher load-carrying limits
than the original wheels and tires doesn't change the
GAWR or the GVWR of your vehicle.
NOTICE:
The wrong wheel can cause trouble in bearing
life, brake cooling, speedometer/odometer
calibration, headlamp aim, bumper height,
vehicle ground clearance, stopping distance and
tire clearance to the body and chassis. You could
also have other problems like a tire air
-out.
Used Replacement Wheels
CAUTION:
Putting a used wheel on your vehicle is
dangerous. You can't know how it's been used or
how many miles it's been driven. It could fail
suddenly and cause an accident. If you have to
replace a wheel, use a new GM original
equipment wheel.
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6-64
Foreign materials such as calcium chloride and other
salts, ice melting agents, road oil and tar, tree sap, bird
droppings, chemicals from industrial chimneys, etc., can
damage your vehicle's finish if they remain on painted
surfaces. Wash the vehicle as soon as possible. If
necessary, use non
-abrasive cleaners that are marked
safe for painted surfaces to remove foreign matter.
Exterior painted surfaces are subject to aging, weather
and chemical fallout that can take their toll over a period
of years. You can help to keep the paint finish looking
new by keeping your vehicle garaged or covered
whenever possible.
Protecting Exterior Bright Metal Parts
Bright metal parts should be cleaned regularly to keep
their luster. Washing with water is all that is usually
needed. However, you may use chrome polish on
chrome or stainless steel trim, if necessary.
Use special care with aluminum trim. To avoid
damaging protective trim, never use auto or chrome
polish, steam or caustic soap to clean aluminum. A
coating of wax, rubbed to high polish, is recommended
for all bright metal parts.
Cleaning Tires
To clean your tires, use a stiff brush with a tire cleaner.
NOTICE:
When applying a tire dressing always take care to
wipe off any overspray or splash from all painted
surfaces on the body or wheels of the vehicle.
Petroleum
-based products may damage the paint
finish and tires.
Sheet Metal Damage
If your vehicle is damaged and requires sheet metal
repair or replacement, make sure the body repair shop
applies anti
-corrosion material to the parts repaired or
replaced to restore corrosion protection.
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7-5
Scheduled Maintenance
The services shown in this schedule up to 100,000 miles
(166 000 km) should be performed after 100,000 miles
(166 000 km) at the same intervals. The services shown
after 100,000 miles (166 000 km) should be performed
at those same intervals.
This vehicle has a computer that lets you know when to
change your engine oil. This is not based on mileage,
but on engine revolutions and engine operating
temperature. When the computer has calculated that the
oil needs changing, the Oil Life Indicator will indicate
that a change is necessary.
See ªFootnotesº at the end of this Maintenance Schedule
for further explanation of maintenance services and
Caterpillar

diesel application.
100 Miles (160 km)
Wheel stud nut service. (45)
500 Miles (800 km)
Wheel stud nut service. (45)
1,000 Miles (1 600 km)
Wheel stud nut service. (45)(46)
3,000 Miles (5 000 km)
Engine oil and filter service. (3)(9)
Check fluid levels (or every 3 months, whichever
occurs first). (1)(2)(6)
Clutch pedal free travel service. (10)
Rear axle air shift motor service. (11)
6,000 Miles (10 000 km)
Engine oil and filter service. (3)(9)
Check fluid levels (or every 3 months, whichever
occurs first). (1)(2)(6)
Chassis lubrication service (or every 6 months,
whichever occurs first). (12)
Lubricate door hinge pins and rollers with engine oil.
Wheels and tires service. (15)
Hydraulic brake service (or every 6 months,
whichever occurs first). (7)
Hydraulic parking brake service (or every 6 months,
whichever occurs first). (8)
Clutch pedal free travel service. (10)
9,000 Miles (15 000 km)
Engine oil and filter service. (3)(9)
Check fluid levels (or every 3 months, whichever
occurs first). (1)(2)(6)
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7-6 12,000 Miles (20 000 km)

Engine oil and filter service. (3)(9)

Check fluid levels (or every 3 months, whichever
occurs first). (1)(2)(6)

Chassis lubrication service (or every 6 months,
whichever occurs first). (12)

Lubricate door hinge pins and rollers with engine oil.

Wheels and tires service. (15)

Hydraulic brake service (or every 6 months,
whichever occurs first). (7)

Hydraulic parking brake service (or every 6 months,
whichever occurs first). (8)

Engine drive belts service (or every 12 months,
whichever occurs first). (18)

Clutch pedal free travel service. (10)

Throttle linkage service. (19)

Thermostatically controlled engine cooling
fan service. (4)(20)

Shields and underhood insulation service. (4)(5)(21)

Check air brake relay valve operation and check for
leaks (or every month, or every 300 hours,
whichever occurs first).
15,000 Miles (25 000 km)

Engine oil and filter service. (3)(9)

Check fluid levels (or every 3 months, whichever
occurs first). (1)(2)(6)

Steering system service. (13)

Front and rear suspension service. (14)

Spring
-to-axle U-bolts and shackle bolts service. (16)

Exhaust system service (or every 6 months,
whichever occurs first). (3)(4)(17)

Air brake service (or every 6 months, whichever
occurs first). (39)
18,000 Miles (30 000 km)

Engine oil and filter service. (3)(9)

Check fluid levels (or every 3 months, whichever
occurs first). (1)(2)(6)

Chassis lubrication service (or every 6 months,
whichever occurs first). (12)

Inspect door hinge pins and bushings and replace as
necessary. Lubricate door hinge pins and rollers with
engine oil.
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7-7

Replace air conditioning filter dryer (or every
18 months, whichever occurs first, and whenever
refrigerant charge is lost for any reason).

Wheels and tires service. (15)

Hydraulic brake service (or every 6 months,
whichever occurs first). (7)

Hydraulic brake caliper service (or every 6 months,
whichever occurs first). (22)

Hydraulic parking brake service (or every 6 months,
whichever occurs first). (8)

Clutch pedal free travel service. (10)

Clean air brake application valve (or every 3 months,
or every 300 hours, whichever occurs first);
lubricate linkage.
21,000 Miles (35 000 km)

Engine oil and filter service. (3)(9)

Check fluid levels (or every 3 months, whichever
occurs first). (1)(2)(6)
24,000 Miles (40 000 km)

Engine oil and filter service. (3)(9)

Check fluid levels (or every 3 months, whichever
occurs first). (1)(2)(6)
Chassis lubrication service (or every 6 months,
whichever occurs first). (12)

Lubricate door hinge pins and rollers with engine oil.

Wheel bearing (grease type) service (or every
24 months, whichever occurs first, and whenever
hubs are removed). (23)

Wheels and tires service. (15)

Hydraulic brake service (or every 6 months,
whichever occurs first). (7)

Hydraulic parking brake service (or every 6 months,
whichever occurs first). (8)

Engine drive belts service (or every 12 months,
whichever occurs first). (18)

Clutch pedal free travel service. (10)

Throttle linkage service. (19)

Thermostatically controlled engine cooling
fan service. (4)(20)

Shields and underhood insulation service. (4)(5)(21)

Air intake system service (or every 24 months,
whichever occurs first). (4)(5)(24)

Thermostatically controlled air cleaner service
(or every 24 months, whichever occurs first).
(3)(4)(25)

(Continued)
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7-8 24,000 Miles (40 000 km) (Continued)

Evaporative Control System service (if equipped) (or
every 24 months, whichever occurs first). (3)(26)

Rear axle air shift motor service. (11)
Check air brake relay valve operation and check for
leaks (or every month, or every 300 hours,
whichever occurs first).
Air brake chamber service (or every 2 months,
whichever occurs first). (41)
Trailer brake hand control valve service (or every
3 months, or 900 hours, whichever occurs first). (42)
27,000 Miles (45 000 km)
Engine oil and filter service. (3)(9)
Check fluid levels (or every 3 months, whichever
occurs first). (1)(2)(6)
30,000 Miles (50 000 km)
Engine oil and filter service. (3)(9)
Check fluid levels (or every 3 months, whichever
occurs first). (1)(2)(6)
Chassis lubrication service (or every 6 months,
whichever occurs first). (12)
Replace fuel filter(s) (or every 12 months, whichever
occurs first). (3)Air cleaner filter replacement service (or every
24 months, whichever occurs first). (3)(4)(27)
Steering system service. (13)
Front and rear suspension service. (14)
Spring
-to-axle U-bolts and shackle bolts service. (16)
Exhaust system service (or every 6 months,
whichever occurs first). (3)(4)(17)
Air brake service (or every 6 months, whichever
occurs first). (39)
Lubricate door hinge pins and rollers with engine oil.
Wheels and tires service. (15)
Hydraulic brake service (or every 6 months,
whichever occurs first). (7)
Hydraulic parking brake service (or every 6 months,
whichever occurs first). (8)
Clutch pedal free travel service. (10)
Air brake automatic slack adjuster service (or every
500 hours, whichever occurs first). (40)
33,000 Miles (55 000 km)
Engine oil and filter service. (3)(9)
Check fluid levels (or every 3 months, whichever
occurs first). (1)(2)(6)
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7-9 36,000 Miles (60 000 km)

Engine oil and filter service. (3)(9)

Check fluid levels (or every 3 months, whichever
occurs first). (1)(2)(6)

Chassis lubrication service (or every 6 months,
whichever occurs first). (12)

Inspect door hinge pins and bushings and replace as
necessary. Lubricate door hinge pins and rollers with
engine oil.

Replace air conditioning filter dryer (or every
18 months, whichever occurs first, and whenever
refrigerant charge is lost for any reason).

Wheels and tires service. (15)

Hydraulic brake service (or every 6 months,
whichever occurs first). (7)

Hydraulic brake caliper service (or every 6 months,
whichever occurs first). (22)

Hydraulic parking brake service (or every 6 months,
whichever occurs first). (8)

Engine drive belts service (or every 12 months,
whichever occurs first). (18)

Clutch pedal free travel service. (10)

Throttle linkage service. (19)

Thermostatically controlled engine cooling
fan service. (4)(20)
Shields and underhood insulation service. (4)(5)(21)

Check air brake relay valve operation and check for
leaks (or every month, or every 300 hours,
whichever occurs first).

Clean air brake application valve (or every 3 months,
or every 300 hours, whichever occurs first);
lubricate linkage.
39,000 Miles (65 000 km)

Engine oil and filter service. (3)(9)

Check fluid levels (or every 3 months, whichever
occurs first). (1)(2)(6)
42,000 Miles (70 000 km)

Engine oil and filter service. (3)(9)

Check fluid levels (or every 3 months, whichever
occurs first). (1)(2)(6)

Chassis lubrication service (or every 6 months,
whichever occurs first). (12)

Lubricate door hinge pins and rollers with engine oil.

Wheels and tires service. (15)

Hydraulic brake service (or every 6 months,
whichever occurs first). (7)

Hydraulic parking brake service (or every 6 months,
whichever occurs first). (8)

Clutch pedal free travel service. (10)
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