The rear alignment specification for toe on the above listed cars has been changed to:
Rear Toe Setting: + 3/32 in. +/- 3/32 in. total toe-in which is the same as + 3/16 DEG +/- 3/16 DEG total toe-in
Whenever rear alignment is checked, toe should be set accordingly. This is the sum (total) toe of both wheels, which should be split as equally as possible to each wheel when resetting. Rear caster and camber are not adjustable.
Toe setting which exceed the above specification may cause irregular rear tire wear. Usually, this wear may occur within 12,874 to 16,093 km (8,000 to 10,000 miles), with the customer's comment being an increase in tire noise and/or roughness. Close inspection of the rear tires may reveal a cupping type wear pattern.
When this condition is encountered, rear toe should always be measured and reset to + 3/32 +/- 3/32 inch total toe-in (+ 3/16 DEG +/- 3/16 DEG total toe-in). The tires should then be rotated. If severe enough, rear tire replacement may be necessary.
General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.