GMC 2003 C4C042 Owner's Manual page 315

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:
D
You can see cord or fabric showing through the
tire's rubber.
D
The tread or sidewall is cracked, cut or snagged deep
enough to show cord or fabric.
D
The tire has a bump, bulge or split.
D
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
-
radial and bias belted tires
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.
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the vehicle may not
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