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
461

CDL General Knowledge Practice Test 1

1 / 50

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

2 / 50

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

3 / 50

When should a vehicle be inspected?

4 / 50

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

5 / 50

Wheel bearing seals should be checked for

6 / 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.

7 / 50

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

8 / 50

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

9 / 50

Which of the following is NOT a suspension system defect?

10 / 50

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

11 / 50

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

12 / 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.

13 / 50

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

14 / 50

What are the ways to know when to shift?

15 / 50

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

16 / 50

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

17 / 50

When doubling your speed, your braking distance is

18 / 50

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

19 / 50

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

20 / 50

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

21 / 50

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

22 / 50

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

23 / 50

You must turn your headlights on

24 / 50

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

25 / 50

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

26 / 50

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

27 / 50

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

28 / 50

When is it safe to remove the radiator cap?

29 / 50

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

30 / 50

What are special conditions in which you should downshift?

31 / 50

The total stopping distance is reaction distance plus braking distance.

32 / 50

How far ahead should you look?

33 / 50

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

34 / 50

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

35 / 50

Drivers signaling a turn may be a hazard.

36 / 50

Hydroplaning is more likely when tire pressure is high.

37 / 50

What is the minimum tread depth for tires?

38 / 50

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

39 / 50

Antifreeze is only necessary when driving in cold weather conditions

40 / 50

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

41 / 50

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

42 / 50

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

43 / 50

Empty trucks require greater stopping distance.

44 / 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.

45 / 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:

46 / 50

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

47 / 50

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

48 / 50

When should a vehicle be inspected?

49 / 50

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

50 / 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.

Your score is

The average score is 73%