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Question

Difficulty: MediumTires, Wheels, and Rims Inspection

An equipment check on a commercial combination unit reveals several wheel and tire conditions across different axles. Which of the following observations constitutes a regulatory safety violation that prohibits operating the vehicle?

  1. A
    A tandem drive axle tire with a measured tread depth of 332 inch\frac{3}{32}\text{ inch} across all major tread grooves
  2. A front steering axle tire with a measured tread depth of 332 inch\frac{3}{32}\text{ inch} in a major tread grooveAnswer
  3. C
    A trailer axle tire with a measured tread depth of 232 inch\frac{2}{32}\text{ inch} across all major tread grooves
  4. D
    A dual drive wheel assembly maintaining a clearance of 12 inch\frac{1}{2}\text{ inch} between tire sidewalls

Answer

A front steering axle tire with a measured tread depth of 332 inch\frac{3}{32}\text{ inch} in a major tread groove is a safety violation.
Federal commercial motor vehicle regulations specify that front steer axle tires must have at least 432 inch\frac{4}{32}\text{ inch} of tread depth in every major groove. A steer tire with only 332 inch\frac{3}{32}\text{ inch} remaining violates safety standards and requires taking the vehicle out of service until the tire is replaced.

Step-by-Step Solution

1
Recall the regulatory minimum tread depth requirements for commercial motor vehicle axles.
Front steer axle tires require a minimum of 432 inch\frac{4}{32}\text{ inch} in every major groove, while all other tires (drive, trailer, tag) require a minimum of 232 inch\frac{2}{32}\text{ inch}.
Steering tires carry critical lateral guidance loads and require greater tread depth to prevent hydroplaning and loss of directional control.
2
Compare the recorded physical measurements and physical conditions against federal safety limits.
The steer axle tire measuring 332 inch\frac{3}{32}\text{ inch} is below the mandatory 432 inch\frac{4}{32}\text{ inch} threshold, whereas all other drive and trailer tire measurements meet or exceed their respective 232 inch\frac{2}{32}\text{ inch} limit.
Operating a commercial motor vehicle with steer tire tread depth below the required standard is an immediate out-of-service violation.

Key Concept

Commercial Motor Vehicle Tire Tread Depth and Inspection Standards
Estimated Time:1m 15s
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Topics

Tires, Wheels, and Rims Inspection

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