GMC 2003 GMT560 T-Series, Owner'S Manual, Page: 210 / 284

Dual Tire Operation
When the vehicle is new, check the wheel nut tightness
on all wheels with a torque wrench after your first
100 miles (160 km) and then 1,000 miles (1 600 km) after
that. Whenever a wheel, wheel bolt or wheel nut is
removed or serviced, repeat the 100 miles (160 km), and
then 1,000 mile (1 600 km) wheel nut tightness check.
See Tightening the Wheel Nuts on page 5-55 for wheel
nut tightening information and proper torque values.
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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.
See Tires on page 5-52 and Inflation -- Tire Pressure on
page 5-53 for more information on proper tire inflation.
When It Is 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.
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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.
5-54