2008 GMC Sierra 1500 Pickup Owner's Manual - Page 401

{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 you change a wheel, remove any rust or dirt from 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. See Changing a Flat Tire on page 5-81. 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. Because the nuts might come loose. The vehicle's wheel could fall off, causing a crash. 7. Put the wheel nuts back on with the rounded end of the nuts toward the wheel after mounting the spare. Tighten each wheel nut by hand. Then use the wheel wrench to tighten the nuts until the wheel is held against the hub. 8. Turn the wheel wrench counterclockwise to lower the vehicle. Lower the jack completely. 5-89