GMC 2003 C4C042 Owner's Manual page 319

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 a crash. 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 after your first 100 miles (160 km), and
then 1,000 miles (1 600 km) after that. Be sure to repeat
this service whenever you have a tire removed or
serviced. See "Maintenance Schedule" in the Index for
further information.
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