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Question

Difficulty: MediumWheels and Tires

When running a hand across the tread ribs of a front tire, a technician feels that one edge of each tread block is smooth while the opposite edge is sharp and jagged. Which wheel alignment setting is most likely out of specification?

  1. A
    Camber angle
  2. Toe settingAnswer
  3. C
    Brake caliper alignment
  4. D
    Differential pinion angle

Answer

The toe setting is most likely out of specification, as incorrect toe creates a classic feathered wear pattern across the tread ribs.
The toe setting controls whether the front edges of the tires point inward or outward relative to the vehicle centerline. When toe-in or toe-out is excessive, the tires scrub sideways against the pavement as they roll forward, resulting in characteristic feathered or sawtooth tread wear.

Step-by-Step Solution

1
Analyze the reported symptom and wear characteristic
The symptom describes tread blocks that are smooth on one side and sharp on the other across the face of the tire, which defines feathered edge wear.
Identifying the specific wear signature is necessary to determine the root mechanical cause.
2
Relate feathered tread wear to suspension and steering geometry
Feathering occurs when tires point excessively inward (toe-in) or outward (toe-out), forcing the tire to drag or scrub sideways across the road surface during forward travel.
Sideway scrub pulls and rounds one edge of each tread rib while leaving a raised, sharp lip on the trailing edge.
3
Rule out non-toe mechanical factors
Camber causes single-shoulder smooth wear, worn dampers cause scalloped cupping, and brake or differential faults do not produce directional tread feathering.
Eliminating alternative alignment and chassis faults confirms the toe adjustment as the correct remedy.

Key Concept

Tire Tread Feathering and Wheel Toe Alignment
Estimated Time:1m 0s
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Topics

Wheels and Tires

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