Safe Driving Practices

Study questions with answers

12 sample Safe Driving Practices questions with the correct answer, a short explanation, and the official handbook reference. Read through them, then take the quiz above.

1. 1. Why is a leaking or broken exhaust system especially dangerous to the driver?

   Correct answer: It can let poisonous fumes into the cab

   A damaged exhaust system can allow poisonous fumes such as carbon monoxide to enter the cab or sleeper berth, which can make a driver sleepy or worse.

   Source: North Carolina CDL Driver Handbook — Section 2: Driving Safely (2.1.3)

2. 2. What is the main benefit that antilock braking systems (ABS) provide?

   Correct answer: It helps you keep control and steer during hard braking

   ABS keeps the wheels from locking during hard braking so you can keep steering control; it does not necessarily shorten your stopping distance.

   Source: North Carolina CDL Driver Handbook — Section 2: Driving Safely (2.18)

3. 3. What are the two special situations in which the manual says you should downshift?

   Correct answer: Before a hill and before a curve

   You should downshift before starting down a hill and before entering a curve, so the engine helps control speed and the vehicle stays stable.

   Source: North Carolina CDL Driver Handbook — Section 2: Driving Safely (2.3.1)

4. 4. For tires other than the front steering-axle tires, how much tread depth must remain in each major groove?

   Correct answer: 2/32 of an inch

   Tires that are not on the steering axle may be worn to a minimum of 2/32 of an inch of tread; front tires require twice that amount.

   Source: North Carolina CDL Driver Handbook — Section 2: Driving Safely (2.1.3)

5. 5. A load with a high center of gravity is most dangerous in what situation?

   Correct answer: In curves or sudden swerves

   A high center of gravity makes a vehicle more likely to tip over, and it is most dangerous in curves or when you must swerve to avoid a hazard.

   Source: North Carolina CDL Driver Handbook — Section 3: Transporting Cargo Safely (3.2.3)

6. 6. What is the purpose of a front-end header board, or 'headache rack'?

   Correct answer: To protect the driver from forward-shifting cargo

   A header board protects the driver by blocking cargo from sliding forward into the cab during a crash or hard stop.

   Source: North Carolina CDL Driver Handbook — Section 3: Transporting Cargo Safely (3.3.3)

7. 7. Which headlights give you the best visibility in fog?

   Correct answer: Low beams

   Low-beam headlights (and fog lights) give the best visibility in fog; high beams reflect off the fog and reduce what you can see.

   Source: North Carolina CDL Driver Handbook — Section 2: Driving Safely (2.12)

8. 8. What is generally the best advice for driving in dense fog?

   Correct answer: Avoid driving and pull off until it clears

   The manual's best advice for fog is simply not to drive — wait it out at a rest stop or truck stop until you can see better; if you must go on, use low beams.

   Source: North Carolina CDL Driver Handbook — Section 2: Driving Safely (2.12)

9. 9. Shortly after changing a tire and driving a short distance, what should a driver do?

   Correct answer: Re-check that the wheel nuts are still tight

   Because lug nuts can settle after a wheel is remounted, you should stop after driving a little way and re-check that the nuts are still tight.

   Source: North Carolina CDL Driver Handbook — Section 2: Driving Safely (2.1.3)

10. 10. At minimum, how many tie-downs are needed for each 10 feet of cargo?

    Correct answer: One

    Use at least one tie-down for every 10 feet of cargo length, and never fewer than two tie-downs on any load.

    Source: North Carolina CDL Driver Handbook — Section 3: Transporting Cargo Safely (3.3.2)

11. 11. What is the least amount of tread that must remain in every major groove of a commercial vehicle's steering-axle (front) tires?

    Correct answer: 4/32 of an inch

    Front tires carry the steering and much of the braking load, so the manual sets a higher wear limit for them: at least 4/32 of an inch of tread in each major groove.

    Source: North Carolina CDL Driver Handbook — Section 2: Driving Safely (2.1.3)

12. 12. During the seven-step inspection, why should the driver take the ignition key along while walking around the vehicle?

    Correct answer: To prevent anyone from starting or moving it while you inspect

    Keeping the key with you ensures no one can start or move the vehicle while you are outside inspecting it.

    Source: North Carolina CDL Driver Handbook — Section 2: Driving Safely (2.1.5)