CDL Commercial License Prep practice questions and answers 2026. Tap an option to test yourself — you'll see the correct answer and a plain-English explanation for every question. Free, no login.
Q11What should be verified when inspecting the fifth wheel coupling device?
✓ Correct answer: B. Locking jaws are fully engaged around the kingpin
When inspecting the fifth wheel coupling device, you must verify that all locking jaws are fully engaged around the kingpin to ensure secure attachment between the tractor and trailer.
Q12When inspecting the vehicle's exhaust system, which condition would require immediate attention?
✓ Correct answer: A. Exhaust leaks near seams or connections
Exhaust leaks near seams or connections require immediate attention because they could allow harmful gases to enter the cab, posing a serious health hazard to the driver.
Q13Which of the following is NOT part of a proper fuel system inspection?
✓ Correct answer: D. Checking the vehicle's fuel economy
Checking the vehicle's fuel economy is not part of a proper fuel system inspection. Fuel system inspections focus on safety issues like leaks, secure mounting, and proper cap sealing.
Q14What is the proper way to check for steering wheel free play during a pre-trip inspection?
✓ Correct answer: C. Turn the steering wheel gently until resistance is felt and measure the movement
The proper way to check for steering wheel free play is to turn the steering wheel gently until resistance is felt and measure the movement before the front wheels begin to pivot, which should not exceed 10 degrees (about 2 inches on a 20-inch steering wheel).
Q15During a brake inspection, what would indicate a brake drum is out of service?
✓ Correct answer: B. Visible cracks extending to the edge of the drum
A brake drum with visible cracks extending to the edge is out of service as these cracks can lead to catastrophic brake failure under load or heat.
Q16What should you verify when checking the vehicle's reflectors?
✓ Correct answer: A. Present, clean, and proper color
When checking reflectors, you should verify they are present, clean, and the proper color (red on rear, amber on sides) to ensure the vehicle is visible to other drivers in low light conditions.
Q17Which of the following would be considered an unsafe condition when inspecting wheel rims?
✓ Correct answer: D. Welding repairs on aluminum wheels
Welding repairs on aluminum wheels are considered unsafe and illegal as they compromise the structural integrity of the wheel, potentially leading to catastrophic failure.
Q18What should be verified when inspecting a vehicle's frame?
✓ Correct answer: C. No cracks or bends in the frame
When inspecting a vehicle's frame, you should verify there are no cracks or bends, as these structural issues can compromise the vehicle's integrity and lead to catastrophic failure.
Q19What is the purpose of checking the vehicle's marker lights during inspection?
✓ Correct answer: B. To ensure they indicate the vehicle's size and dimensions to other drivers
The purpose of checking marker lights is to ensure they are functional and properly indicate the vehicle's size and dimensions to other drivers, especially in low visibility conditions.
Q20When inspecting air brake hoses, which condition would indicate an immediate safety concern?
✓ Correct answer: A. Audible air leaks from hoses or connections
Audible air leaks from hoses or connections indicate an immediate safety concern as they can lead to loss of air pressure, reduced braking capability, and potential brake failure.
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