GM Service Manual Online
For 1990-2009 cars only

The tires and wheels are match-mounted at the assembly plant. Match-mounting aligns the radially stiffest part of the tire, or high spot, to the smallest radius, or low spot, of the wheel. The high spot of the tire is originally marked by a red paint mark or an adhesive label on the outboard sidewall.

The low spot of the wheel will be at the location of the valve stem. Before dismounting a tire from its wheel, scribe a line on the tire at the valve stem to assure that it is remounted in the same position. Replacement tires that are of original equipment quality will have their high and low spot marked in the same manner.