CDL Practice Test


Idaho! You will be presented with 40 questions and you must answer 34 questions correctly to pass.  There is a 50 minute time limit.  You may not go back once you answer a question.  Click the "Start Test" button below to begin.  Good luck!

1 / 40

This carries hydraulic fluid or air to the wheel brake assemby.

2 / 40

You do not have a hazardous materials endorsement on your commercial driver license. When can you legally haul hazardous materials?

3 / 40

Which of the following statements about overhead space is true?

4 / 40

This object releases the fifth wheel locking jaw to allow uncoupling.

5 / 40

Play of the steering wheel should not exceed:

6 / 40

What does the service brake system do?

7 / 40

The crack-the-whip effect is more likely to cause the front trailer to tip over.

8 / 40

The method used to make sure the spring brakes will come on automatically is to:

9 / 40

School buses are one of the safest means of transportation. What two key factors contribute to this impressive safety record?

10 / 40

Students exit the bus and walk:

11 / 40

Do you need to stop before a railroad crossing if you are hauling 100 pounds of Division 4.3 materials?

12 / 40

You should___to reduce the air leakage rate.

13 / 40

With Division 1.2 or 1.3 Explosive B, how close to the travelled part of the roadway can you park?

14 / 40

Within 3 minutes, this gauge pressure should build to 90 psi from 50 psi.

15 / 40

In column 1, the "D" symbol means:

16 / 40

You should make sure the_____before backing under a trailer.

17 / 40

The Emergency Response Guide, ERG, can best be explained as _____.

18 / 40

Select the vehicle that off-tracks the most.

19 / 40

When transporting explosives you may not park:

20 / 40

On the Hazardous Materials Table, column 1 shows:

21 / 40

You should be extra cautious when___while driving a smooth bore tanker combination.

22 / 40

What is the first thing to do if your vehicle catches fire while driving?

23 / 40

What should you do if the low air pressure warning comes on for only one system in a truck or bus that has a dual air brake system?

24 / 40

Which trailer should be the first one after the tractor?

25 / 40

When should the trailer hand valve be used?

26 / 40

Make sure that_____before you back under a trailer.

27 / 40

____is the most common type of foundation brakes used by heavy vehicles.

28 / 40

In the event of a tire failure you should...

29 / 40

A battery box check is important. The battery must be secure, connection must be tight, and cell caps must be present. In addition these items should be checked:

30 / 40

The interlock system for the brake and accelerator on a transit coach may be used:

31 / 40

Select the statement that is true in regards to what is required of a driver with a double or triple trailers:

32 / 40

The direction of liquid movement not prevented by baffles is:

33 / 40

What are spring brakes?

34 / 40

When driving on a clear night with the vehicle lights on, your speed should be such that you can stop within _____.

35 / 40

The purpose for the emergency air line is:

36 / 40

Select the item that is not checked in the engine compartment:

37 / 40

Where are shut off valves located on trailers that are doubles or triples?

38 / 40

You should____when an emergency requires you to quickly stop due to a crash.

39 / 40

The sliding mechanism and locking device for a tandem axle on trailers is:

40 / 40

How should the shut off valves at the rear of the trailer be when inspecting doubles?

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CDL Category Practice Tests

CDL Practice Test

How To Get A idaho Commercial Drivers License

Applicants can be age 18 or older when applying for their CDL. Those under the age of 21 are not eligible for the Hazmat or Doubles/Triples Endorsement. All applicants must get a DOT medical card to shows their ability to be physically able to drive a commercial motor vehicle.

Any drivers that fall into the following categories are disqualified from receiving their CDL:

  • Having more than one driver’s license.
  • Being convicted of an impaired driving offense in a commercial vehicle within the prior 24 months to submitting the CDL application.
  • Current suspended, revoked, denied, or canceled driver’s license.
  • Having CDL disqualifications in other states.

All applicants are required to complete a practical skills test and knowledge test in order to receive their CDL. Adding endorsements to a CDL will require additional knowledge tests and practical skills tests.

T – Doubles / Triples
P – Passenger
N – Tank Vehicles
H – Hazardous Materials
X – Tank Vehicle That Carries Hazardous Materials

Hit the Open Road

idaho CDL License Test Tips

Applicants for an Idaho CDL must complete a written knowledge test to showcase their retention of the commercial driving laws. Class A drivers are required to take a 70 question assessment that includes 20 questions specifically about combination vehicles. Class B and C applicants are required to pass a 50 question assessment. Those seeking endorsements and removal of the Air Brake Restriction must take additional tests that range between 20 and 30 questions. All tests must be passed with a score of 80 percent or better.

CDL applicants are required to pass a three-part skills test. These parts include a driving test, basic control skills test, and vehicle inspection test. This can be completed at an Idaho State Driving Facility or other approved testing site.

Additional Information

Information on the Idaho Transportation Department

The Idaho Transportation Department administers the CDL requirements and testing in Idaho. To get more information contact them via:


Phone:  208.334.8000


Additional Idaho CDL Helpful Links

Please use the links below to access more valuable Idaho CDL testing resources and to learn more about practice driving tests for the state of Idaho.