Wheel Mounting Surface Check

Caution

The use of non-GM original equipment wheels may cause: Damage to the wheel bearing, the wheel fasteners and the wheel Tire damage caused by the modified clearance to the adjacent vehicle components Adverse vehicle steering stability caused by the modified scrub radius Damage to the vehicle caused by the modified ground clearance Speedometer and odometer inaccuracy Replace any wheels that are bent or dented, or have excessive lateral or radial runout. Wheels with runout greater than specified may cause objectionable vibrations. Replacement wheels must be equivalent to the original equipment wheels in the following ways: The load capacity The wheel diameter The rim width The wheel offset The mounting configuration A wheel of the incorrect size or type may affect the following conditions: Wheel and hub-bearing life Brake cooling Speedometer/odometer calibration Vehicle ground clearance Tire clearance to the body and the chassis It is recommended that an approved tire balancer capable of reading lateral and radial runout be used to perform this check following the tire balancer manufacturer instructions. If one is not available, perform the following procedure:

Wheel Mounting Surface Check — figure 1

1. Thoroughly clean the wheel mounting surface (1) with a clean shop towel and denatured alcohol, or equivalent.
2. Use a straight edge 203 - 229 mm (8 - 9 in) in length (2). Place the straight edge (2) on the wheel mounting surface (1). Try to rock the straight edge (2) up and down within the wheel mounting surface (1).
3. For aluminum flat-mount wheels, repeat the procedure in step 2 on at least  3 - 4 different positions on the wheel mounting surface (1).
4. If you can rock the straight edge (2), the mounting surface (1) is bent and the wheel must be replaced.
5. Inspect the mounting wheel/nut holes for damage caused from over-torquing the wheel/nuts. Inspect for collapsed wheel/nut bosses. Inspect for cracked wheel bosses. Replace the wheel if damage is found.

Wheel Mounting Surface Check — figure 2

6. For steel wheels, repeat the procedure in step 2 on at least  3 - 4 different positions on the wheel mounting surface (2).

Note

The outer mounting ring is designed to be raised slightly above the inner mounting ring.

7. If you can rock the straight edge (1), the mounting surface (2) is bent and the wheel must be replaced.

Wheel Mounting Surface Check — figure 3

8. Inspect the mounting wheel/nut holes (1) for damage caused from over-torquing the wheel/nuts. Inspect for collapsed wheel/nut bosses. Inspect for cracked wheel bosses. If damage is found, the wheel must be replaced.
9. Replace the wheel if the wheel is bent.
10. Replace the wheel if the wheel/nut boss area is cracked. Identify steel wheels with a 2 or 3 - letter code stamped into the rim near the valve stem. Aluminum wheels have the code, the part number, and the manufacturer identification cast into the back side of the wheel.