During a pre-trip equipment audit of a commercial tractor-semitrailer fleet, a technician … — Commercial Driver's License (CDL) General Knowledge Exam

During a pre-trip equipment audit of a commercial tractor-semitrailer fleet, a technician evaluates tire condition reports from four different vehicles. Assuming all other components are in proper working order, which vehicle's tire measurements meet the minimum regulatory requirements for immediate highway dispatch?

A
A tractor with a tread depth of $3/32\text{ inch}$ across all steering axle grooves and $4/32\text{ inch}$ across all drive axle grooves
A tractor-trailer combination with $5/32\text{ inch}$ of tread depth on the front steering axle and $3/32\text{ inch}$ of tread depth across all drive and trailer axle tiresAnswer
C
A tractor with a uniform tread depth of $2/32\text{ inch}$ across both the front steering axle and all drive axles
D
A semitrailer with $1/32\text{ inch}$ of tread depth on the inner dual tires and $4/32\text{ inch}$ of tread depth on the outer dual tires of the tandem axle

Answer

The tractor-trailer combination with

5/32\text{ inch}

on the front steering axle and

3/32\text{ inch}

across all drive and trailer axle positions meets all regulatory minimum standards.

Commercial motor vehicle safety regulations require a minimum tread depth of

4/32\text{ inch}

in every major groove on front steer tires and at least

2/32\text{ inch}

on all other tires. The combination with

5/32\text{ inch}

on the steer axle and

3/32\text{ inch}

on the drive and trailer axles safely exceeds both thresholds.

Step-by-Step Solution

Identify the federal and state commercial motor vehicle minimum tread depth standards by axle position.

Front steering axle tires require at least

4/32\text{ inch}

of tread depth in every major groove, while all other tires (drive and trailer axles) require at least

2/32\text{ inch}

Steering tires require greater tread depth to maintain directional control, prevent hydroplaning, and handle high lateral cornering forces.

Evaluate the steering axle measurements for each vehicle against the

4/32\text{ inch}

requirement.

Vehicles with

3/32\text{ inch}

and

2/32\text{ inch}

on their steering axles fail the minimum threshold immediately.

Operating a commercial motor vehicle with less than

4/32\text{ inch}

on the front steering axle is an out-of-service safety violation.

Evaluate the non-steering axle (drive and trailer) measurements against the

2/32\text{ inch}

requirement.

The configuration with

5/32\text{ inch}

on steer tires and

3/32\text{ inch}

on all drive and trailer tires satisfies both thresholds (

5/32\text{ inch} \ge 4/32\text{ inch}

and

3/32\text{ inch} \ge 2/32\text{ inch}

All wheel positions independently meet or exceed their respective statutory minimums.

Key Concept

Axle-Specific Commercial Vehicle Minimum Tread Depth Requirements

Estimated Time:1m 30s

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Step-by-Step Solution

Key Concept

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