Page 239 of 331

6-44
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.
Dual Tire Operation
When the vehicle is new, or whenever a wheel, wheel
bolt or wheel nut is replaced, check the wheel nut 
torque after 100, 1,000 and 6,000 miles (160, 1 600 and
10 000 km) of driving. 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 ªTiresº 
and ªInflation 
- Tire Pressureª in the Index for more
information on proper tire inflation.
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. 
     
        
        Page 240 of 331
6-45 Tightening the Wheel Nuts
All wheel nuts must be properly tightened. With a
torque wrench, tighten the wheel nuts firmly in a
crisscross sequence using the proper wheel nut torque.
Front Rear
CAUTION:
Incorrect wheel nuts or improperly tightened
wheel nuts can cause the wheel to become loose
and even come off. This could lead to a crash. 
Be sure to use the correct wheel nuts. If you have
to replace them, be sure to get new GM original
equipment wheel nuts.
Tighten with a torque wrench to the proper torque.
When the vehicle is new, or whenever a wheel, wheel bolt    
or wheel nut is replaced on a dual wheel setup, check 
the wheel nut torque after 100, 1,000 and 6,000 miles 
(60, 1 600 and 10 000 km) or driving. For proper torque
specifications, see ªWheel Nut Torqueº in the Index. 
     
        
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6-49
NOTICE:
The wrong wheel can also cause problems with
bearing life, brake cooling, speedometer or
odometer calibration, headlamp aim, bumper
height, vehicle ground clearance and tire or tire
chain clearance to the body and chassis.
Whenever a wheel, wheel bolt or wheel nut is replaced
on a dual wheel setup, check the wheel nut torque after
100, 1,000 and 6,000 miles (160, 1 600 and 10 000 km)
of driving. For proper torque, see ªWheel Nut Torqueº
in the Index.
See ªTightening the Wheel Nutsº in the Index for 
more information.Used Replacement Wheels
CAUTION:
Putting a used wheel on your vehicle is dangerous.
You can't know how it's been used or how far it's
been driven. It could fail suddenly and cause a
crash. If you have to replace a wheel, use a new
GM original equipment wheel. 
     
        
        Page 261 of 331
6-66
Replacement Bulbs
Lamps  Quantity Number
Sealed Beam Headlamps 2 H6054
Front Marker Lamp 2 194
Front Parking and Turn Lamp 4 2357NA
Rear Parking Lamp 2 3057
Rear Stop and Turn Lamp 2 3057
Back
-up Lamp2 3156
Roof Marker Lamps 5 194
For any bulb not listed here, contact your dealer.
Capacities and Specifications
All capacities are approximate. When adding, be sure 
to fill to the appropriate level or as recommended in 
this manual.
Please refer to ªRecommended Fluids and Lubricantsº
in the Index for more information.
Engine TypeVIN
CodeSpark Plug 
Gap
ªVORTECº 8100 V8 G 0.060 inches 
(1.52 mm)
Wheels and Tires
Model Description Torque
Front 5 bolts (5/8 in.)
175 lb
-ft (240 N´m)
Rear 10 bolts (5/8 in.)
175 lb
-ft (240 N´m)
Tire Pressure See the Certification/Tire label on the
rear edge of the driver's door or the 
incomplete vehicle document in the cab.