Pontiac G5 2009 Owner's Manual page 337

CAUTION:
{
Rust or dirt on a wheel, or on the parts to which it is
fastened, can make wheel nuts become loose after
time. The wheel could come off and cause an
accident. When changing a wheel, remove any rust
or dirt from places where the wheel attaches to the
vehicle. In an emergency, 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.
See Changing a Flat Tire on page 5-84.
10. Remove any rust or dirt
from the wheel bolts,
mounting surfaces, and
spare wheel.
5-93