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Difficulty: Very hardTires, Wheels, and Rims Inspection

A fleet maintenance supervisor is auditing a driver's inspection report for a loaded 5-axle combination vehicle. The report details the physical condition of the right-side dual wheel assembly on the rearmost drive axle:

I. Tread depths are measured at 3/32-inch on the inner tire and exactly 2/32-inch on the outer tire across all major grooves.
II. Both tires are identical in size and feature radial construction, though they are produced by different manufacturers.
III. The gap between the dual tires is free of debris, but the tire sidewalls are visibly touching each other at the bottom where they compress under the cargo weight.
IV. The outer steel wheel rim has a smooth, integrated weld where a mechanic previously repaired a small rim crack.

Based on federal commercial vehicle inspection standards, which combination of these logged items represents definitive safety violations that prohibit the vehicle from being driven?

  1. Items III and IV onlyAnswer
  2. B
    Items I, III, and IV only
  3. C
    Items I and IV only
  4. D
    Items I, II, and III only

Answer

The correct combination of safety violations is Items III and IV only.
The correct answer accurately identifies Items III and IV as the only true violations. Dual tires that come in physical contact with each other (Item III) create severe friction and heat, risking a blowout or fire. Furthermore, any welding repairs on wheel rims (Item IV) are strictly prohibited, regardless of application quality, as welding destroys the metal's structural integrity. Item I is legally compliant because drive axle tires require a minimum tread depth of exactly 2/32-inch. Item II is compliant because mixing manufacturers is permitted as long as the size and radial/bias classification match.

Step-by-Step Solution

1
Evaluate Item I regarding tread depth on the drive axle.
Determined as compliant. Drive axle tires require a minimum of 2/32-inch tread depth. Both the 3/32-inch and 2/32-inch measurements meet this exact standard.
Federal regulatory thresholds explicitly differentiate between steer axles (4/32-inch minimum) and all other axles (2/32-inch minimum).
2
Evaluate Item II regarding mismatched tire manufacturers.
Determined as compliant. As long as the dual tires share the exact same physical size and radial/bias construction type, mixing manufacturers is legally permitted.
Regulations strictly prohibit mixing tire types (e.g., radial vs. bias) on the same axle due to handling differences, but do not mandate brand uniformity.
3
Evaluate Item III regarding dual tire sidewalls touching.
Identified as a critical violation. Dual tires must never make physical contact with each other or any vehicle components under load.
Friction between touching dual tires under load generates extreme heat, which predictably leads to catastrophic tire blowouts or vehicle fires.
4
Evaluate Item IV regarding the welded wheel rim repair.
Identified as a critical violation. Any form of welding repair on commercial wheel rims is strictly prohibited across all jurisdictions.
Welding permanently alters the temper and structural integrity of the steel, making the rim highly prone to catastrophic failure under operational stress.

Key Concept

Commercial Motor Vehicle Tire and Wheel Inspection Criteria
Estimated Time:1m 30s
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Topics

Tires, Wheels, and Rims Inspection

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