GMC 2006 Envoy Owner's Manual page 437

CAUTION:
{
Rust or dirt on the 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 a paper towel to do this; but be sure to use
a scraper or wire brush later, if needed, to get
all the rust or dirt off.
7. Remove all the wheel
nuts and take off the
flat tire.
9. Place the spare tire on the wheel-mounting surface.
8. Remove any rust or dirt
from the wheel bolts,
mounting surfaces
and spare wheel.
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