ASE A4 Suspension and SteeringWheels and Tires Diagnosis and RepairMedium
A technician is inspecting a wheel for damage. They observe small cracks originating from the lug nut holes on an aluminum alloy wheel. This type of damage is commonly referred to as:
- AStress cracks
- BLateral runout
- CCurb rash
- DRadial runout
Show answer & explanationAnswer & explanation
Correct answer: A. Stress cracks
Cracks originating from the lug nut holes are typically stress cracks, often caused by improper lug nut torque (over-tightening or uneven tightening) or repeated stress cycles, which compromise the structural integrity of the wheel.
Why the other options are wrong
- B. Lateral runout is a measure of how much a wheel wobbles side-to-side, not a type of crack.
- C. Curb rash is cosmetic damage to the outer edge of the rim from contact with a curb, not structural cracks around lug holes.
- D. Radial runout is a measure of how out-of-round a wheel is, not a type of crack.
Wheel Stress Cracks
Structural cracks in a wheel, often originating from high-stress points like lug nut holes, indicating compromised integrity.
- Can be caused by improper lug nut torque (over-tightening or uneven).
- Also result from impact damage or material fatigue.
- Render the wheel unsafe and require replacement.
Memory trick: Cracks at the lugs mean 'stress' and a wheel that's a bust!