CDL General Knowledge Practice Test 2025

CDL General Knowledge Practice Test 2025 Commercial Driver’s License Permit Test (CDL) in the USA: Try our free original CDL Knowledge Practice questions answers.

There is a total of 50 CDL General Knowledge Practice Question Answers with explanations.  You must pass the written test for the CDL that you need. In general, the CDL general knowledge test is required to be taken by all CDL applicants. The CDL test consists of 50 questions. To pass, you must correctly answer at least 40 questions (80%).

CDL General Knowledge Practice Test

Test Name CDL Practice Test 2025
Language English
License CDL (Class A, B, or C),
Total Questions 50 Knowledge Practice Test
Test For Commercial Driver License
Test Preparation Driving Knowledge
Country USA
Explanation Yes
0%
0 votes, 0 avg
407

CDL General Knowledge Practice Test 1

1 / 50

When water collects on the road and your tires lose contact with the road, this is called

2 / 50

Most people can tell when they are sleepy or about to fall asleep.

3 / 50

When stopped on a hill, how do you prevent a vehicle from rolling back?

4 / 50

Which of the following factors should you take into consideration when determining a safe speed for going down a long, steep downgrade? Choose all that apply.

5 / 50

When doubling your speed, your braking distance is

6 / 50

Where should your reflectors be placed when stopped on a divided highway?

7 / 50

If there is no white stop line painted on the pavement of a railroad crossing, vehicles that are required to stop must stop:

8 / 50

During a vehicle inspection test, you should put the starter switch key in your pocket

9 / 50

The act of operating a motor vehicle in a selfish, bold, or pushy manner, without regard for the rights and safety of others is called:

10 / 50

Empty trucks require greater stopping distance.

11 / 50

You must turn your headlights on

12 / 50

You should shift your transmission to a low gear before starting a downgrade.

13 / 50

When going down a long and/or steep downgrade, you should release the brakes after your speed has been reduced to:

14 / 50

To test hydraulic brakes for leaks, pump the pedal 3 times. Then apply firm pressure to the pedal and hold for 5 seconds. The pedal should move. If it doesn’t, there may be a leak or other problem.

15 / 50

The total stopping distance is reaction distance plus braking distance.

16 / 50

Driving with wet brakes can cause which of the following. Choose all that apply

17 / 50

When should a vehicle be inspected?

18 / 50

When driving in very hot weather, how often should you check the tires?

19 / 50

To determine how many seconds of following distance space you have, wait until a vehicle ahead passes a shadow on the road, a pavement marking, or some other clear landmark and then count the seconds until you reach the same spot and then double it.

20 / 50

What is the minimum tread depth for tires?

21 / 50

What are the ways to know when to shift?

22 / 50

Antifreeze is only necessary when driving in cold weather conditions

23 / 50

If you are driving a 30 foot vehicle at 35 mph, how many seconds of following distance should you allow?

24 / 50

How long does it take a typical tractor trailer unit to clear a double track?

25 / 50

If weather conditions require the use of windshield wipers, you must also turn on your headlights.

26 / 50

Wheel bearing seals should be checked for

27 / 50

When backing a vehicle, you should back and turn towards what side?

28 / 50

If an oncoming driver had drifted into your lane, what should you do?

29 / 50

If an aggressive driver is involved in an accident, you should stop immediately and help them; the same as you would for any other driver.

30 / 50

When is it safe to remove the radiator cap?

31 / 50

What are special conditions in which you should downshift?

32 / 50

During very hot weather, you should let the air out the tires to prevent a blowout.

33 / 50

For vehicles with automatic transmissions, you can select a low range to get greater engine braking when going down grades.

34 / 50

Hydroplaning is more likely when tire pressure is high.

35 / 50

What is the most important hand signal you can your helper should agree on?

36 / 50

If you are driving a 30 foot vehicle at 55 mph, how many seconds of following distance should you allow?

37 / 50

Which of the following is NOT a suspension system defect?

38 / 50

You should turn retarders on whenever the road is wet, icy, or snow covered.

39 / 50

Which of the following is a NOT a steering system part?

40 / 50

Drivers signaling a turn may be a hazard.

41 / 50

What types of vehicles can get stuck on a railroad crossing?

42 / 50

When should a vehicle be inspected?

43 / 50

Why is it important to use a helper when backing a vehicle?

44 / 50

Stopping is not always the safest thing to do in an emergency.

45 / 50

A vehicle must be equipped with 3 kinds of emergency equipment. Which of the following is NOT one of them?

46 / 50

If you are being tailgated, what should you NOT do?

47 / 50

How far ahead should you look?

48 / 50

For use as warning devices for parked vehicles, how many red reflective triangle should you carry?

49 / 50

A thin layer of ice that is clear enough that you can see the road underneath is called

50 / 50

If your brakes fail on a long downgrade, your best bet is to

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The average score is 73%