Wheel Mounting Surface Check

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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.

Fig 1: Placing Straight Edge On Wheel Inboard Mounting Surface

Courtesy of GENERAL MOTORS CORP.

Use a straight edge 203-229 mm (8-9 in) long. Place the straight edge on the wheel inboard mounting surface. Try to rock the straight edge up and down within the mounting surface.

Fig 2: Placing Straight Edge On Different Positions On Inboard Mounting Surface
Courtesy of GENERAL MOTORS CORP.
Repeat this procedure on at least 3-4 different positions on the inboard mounting surface.
- The outer ring of the mounting surface normally is raised above everything inside the mounting surface.
- The mounting surface will be raised above the outer ring if the wheel mounting surface has been bent on a tire changer.
- If you can rock the straight edge, the mounting surface is bent and you must replace the wheel.
  
  Fig 3: Inspecting Mounting Wheel/Nut Holes
  Courtesy of GENERAL MOTORS CORP.
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.
NOTE: 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
  Important :
- 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
Replace the wheel if the wheel is bent.
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.