GMC 2007 Yukon XL Owner's Manual page 517

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.
6. Remove any rust or
dirt from the wheel
bolts, mounting
surfaces and spare
wheel.
CAUTION:
{
Never use oil or grease on studs or nuts.
If you do, the nuts might come loose.
Your wheel could fall off, causing a
serious accident.
7. Put the wheel nuts back on with the rounded
end of the nuts toward the wheel after
mounting the spare tire.
8. Tighten each wheel nut by hand. Then use
the wheel wrench to tighten the nuts until the
wheel is held against the hub.
517