2008 Buick LaCrosse Owner's Manual - Page 362

{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 5-87. 7. Remove any rust or dirt from the wheel bolts, mounting surfaces, and spare wheel. 8. Install the compact spare tire. 5-92