TheoryFree CDL Commercial License Prep Practice Test
Take a free CDL Commercial License Prep practice test for 2026 with questions, answers, explanations, PDF download and timed mock exam links.
CDL Commercial License Prep Questions
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Q1During a pre-trip inspection, which tire condition would most likely cause a vehicle to be placed out of service?
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✓ Correct answer: Tread depth below 2/32 inch on steering tires
Tread depth below 2/32 inch on steering tires is a critical safety violation that would place a commercial vehicle out of service, as it significantly increases the risk of blowouts and loss of vehicle control.
Q2What is the proper method for checking brake adjustment on a commercial vehicle?
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✓ Correct answer: Measure the pushrod travel when brakes are applied
The correct method for checking brake adjustment is to measure the pushrod travel when brakes are applied, which determines if the brakes are properly adjusted for optimal stopping performance.
Q3Which of the following is NOT a required item to check during a steering component inspection?
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✓ Correct answer: Navigation system functionality
While steering components must be thoroughly inspected, the vehicle's navigation system is not part of the required steering component inspection as it doesn't affect the mechanical operation of the steering system.
Q4When inspecting air brake slack adjusters, what is the maximum allowable free play for most commercial vehicles?
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✓ Correct answer: 1/4 inch
The maximum allowable free play for most commercial vehicle slack adjusters is 1/4 inch, beyond which brake performance would be compromised and could result in an out-of-service violation.
Q5Which emergency equipment item is NOT typically required to be carried on a commercial motor vehicle?
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✓ Correct answer: First aid kit
While fire extinguishers, warning triangles, and spare fuses are required emergency equipment items, a first aid kit is not federally mandated equipment for all commercial motor vehicles (though it is recommended).
Q6What condition would make headlights fail inspection?
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✓ Correct answer: Different colored headlights
Different colored headlights would fail inspection as they violate regulations requiring matched, properly colored lights for visibility and to avoid confusing other drivers.
Q7During a cargo securement inspection, which of the following would indicate a violation?
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✓ Correct answer: Cargo shifting more than 1 inch in any direction
Cargo shifting more than 1 inch in any direction indicates inadequate securement, which violates safety regulations and creates a serious hazard for safe vehicle operation.
Q8What is the minimum tread depth requirement for non-steering tires on a commercial vehicle?
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✓ Correct answer: 1/32 inch
The minimum legal tread depth for non-steering tires on a commercial vehicle is 1/32 inch, though many safety experts recommend more than the minimum for optimal safety.
Q9What should you check on windshield wipers during a pre-trip inspection?
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✓ Correct answer: Proper tension against the windshield
During a pre-trip inspection, you should check that windshield wipers have proper tension against the windshield to ensure they can effectively clear precipitation for safe visibility.
Q10When inspecting a vehicle's suspension system, which of the following would be considered a critical defect?
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✓ Correct answer: Cracked or broken leaf spring
A cracked or broken leaf spring is considered a critical defect during suspension inspection as it can lead to complete suspension failure, loss of vehicle control, and potentially serious accidents.
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