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Difficulty: Very hardTires, Wheels, and Rims Inspection

A commercial driver is reviewing a digital Driver Vehicle Inspection Report (DVIR) for a 5-axle combination vehicle prior to dispatch. The report details the physical condition of the tires and wheel assemblies across multiple axles. Based on federal commercial vehicle safety regulations, which of the following documented findings is an explicit safety violation that prohibits the vehicle from being driven?

  1. A steel wheel rim on a trailer axle that features a seamless, machine-welded repair over a previous structural crack.Answer
  2. B
    Drive axle dual tires that have worn down to exactly 3/32-inch of tread depth in every major groove.
  3. C
    Front steering axle tires that measure exactly 4/32-inch of tread depth in all major grooves and show minor surface scuffing on the sidewalls.
  4. D
    Trailer axle wheels equipped with recapped (retreaded) tires that currently measure exactly 2/32-inch of tread depth.

Answer

A steel wheel rim on a trailer axle that features a seamless, machine-welded repair over a previous structural crack.
According to the Federal Motor Carrier Safety Regulations (FMCSRs), wheels and rims must not be cracked or broken, and any repairs by welding to wheels and rims are strictly prohibited. A welded repair, regardless of how professionally it appears to be done, fundamentally compromises the structural integrity of the wheel and requires the vehicle to be placed out of service immediately.

Step-by-Step Solution

1
Evaluate the tread depth measurements provided in the options against the regulatory minimums.
Steer tires require at least 4/32-inch of tread, while drive and trailer tires require at least 2/32-inch. All tire options presented (4/32-inch on steer, 3/32-inch on drive, 2/32-inch on trailer) meet their respective minimum legal thresholds without falling below them.
To systematically rule out tire wear as the source of the regulatory violation.
2
Assess the legality of the specific tire modifications and rim conditions described in the remaining scenarios.
Retreaded tires are permitted on trailer axles, and minor sidewall scuffing without exposed cord is legally acceptable. However, welded repairs on any commercial wheel rim are strictly prohibited.
To identify the condition that explicitly violates Federal Motor Carrier Safety Regulations (FMCSRs) and mandates an out-of-service designation.

Key Concept

Federal motor carrier regulations mandate specific minimum tread depths (4/32-inch for steer tires, 2/32-inch for all others) and strictly prohibit any welded repairs on commercial vehicle wheels or rims.
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Topics

Tires, Wheels, and Rims Inspection

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