CDL GENERAL KNOWLEDGE
MASTERY TEST QUESTIONS AND
ANSWERS
1. What is the minimum tread depth required for steering axle tires?
A. 2/32 inch
B. 6/32 inch
C. 4/32 inch
D. 1/32 inch
Answer: C
Conceptual Explanation: Federal regulations require a minimum tread depth of 4/32 inch
for front (steering) tires to ensure adequate grip and water displacement.
2. When testing a hydraulic braking system for leaks, you should pump the brake pedal three
times and then apply firm pressure for five seconds. The pedal should not move for how
long?
A. 5 seconds
B. 10 seconds
,C. 15 seconds
D. 30 seconds
Answer: A
Conceptual Explanation: If the pedal moves during the 5-second hold, there may be a leak
or other functional problem in the hydraulic system.
3. Which of these is a sign of tire failure?
A. All of the above
B. A loud bang
C. Steering that feels heavy
D. Vibration
Answer: A
Conceptual Explanation: Tire failure can manifest as physical vibrations, audible
blowouts, or a sudden change in steering resistance.
4. How many red reflective triangles should you carry for emergency stops?
A. 1
B. 2
C. 3
D. 4
, Answer: C
Conceptual Explanation: Drivers are required to carry three red reflective triangles to be
placed at specific distances to warn other motorists.
5. What is ‘black ice’?
A. Ice mixed with mud
B. Ice that forms only at night
C. A thin layer of ice clear enough to see the road underneath
D. Frozen exhaust fumes on the road
Answer: C
Conceptual Explanation: Black ice is a thin, nearly invisible coating of ice that makes the
road look wet when it is actually extremely slippery.
6. When double-clutching, what should you use the tachometer for?
A. To monitor oil pressure
B. To monitor the turbocharger boost
C. To check the electrical load
D. To tell you when to shift
Answer: D
MASTERY TEST QUESTIONS AND
ANSWERS
1. What is the minimum tread depth required for steering axle tires?
A. 2/32 inch
B. 6/32 inch
C. 4/32 inch
D. 1/32 inch
Answer: C
Conceptual Explanation: Federal regulations require a minimum tread depth of 4/32 inch
for front (steering) tires to ensure adequate grip and water displacement.
2. When testing a hydraulic braking system for leaks, you should pump the brake pedal three
times and then apply firm pressure for five seconds. The pedal should not move for how
long?
A. 5 seconds
B. 10 seconds
,C. 15 seconds
D. 30 seconds
Answer: A
Conceptual Explanation: If the pedal moves during the 5-second hold, there may be a leak
or other functional problem in the hydraulic system.
3. Which of these is a sign of tire failure?
A. All of the above
B. A loud bang
C. Steering that feels heavy
D. Vibration
Answer: A
Conceptual Explanation: Tire failure can manifest as physical vibrations, audible
blowouts, or a sudden change in steering resistance.
4. How many red reflective triangles should you carry for emergency stops?
A. 1
B. 2
C. 3
D. 4
, Answer: C
Conceptual Explanation: Drivers are required to carry three red reflective triangles to be
placed at specific distances to warn other motorists.
5. What is ‘black ice’?
A. Ice mixed with mud
B. Ice that forms only at night
C. A thin layer of ice clear enough to see the road underneath
D. Frozen exhaust fumes on the road
Answer: C
Conceptual Explanation: Black ice is a thin, nearly invisible coating of ice that makes the
road look wet when it is actually extremely slippery.
6. When double-clutching, what should you use the tachometer for?
A. To monitor oil pressure
B. To monitor the turbocharger boost
C. To check the electrical load
D. To tell you when to shift
Answer: D
