CDL Practice Test


Below are practice questions for the Iowa CDL test. The site is free and you are able to take the practice test as many times as you need to as you prepare to obtain your Iowa CDL. The questions and answers covered in these Iowa practice CDL tests are taken from the Iowa DOT CDL manual. 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.

1 / 40

What is the safest way to stop unruly behavior on the bus?

2 / 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:

3 / 40

What is the earliest way to notice a trailer skid?

4 / 40

What method should be used to test that the air is flowing to all the trailers?

5 / 40

It has just reached freezing. Which of the following areas is slippery?

6 / 40

Is it important to look into the back of the fifth wheel to see if the lockpin is locked in?

7 / 40

When inspecting the ______you are making sure that the lines and hoses are not chafed, cut, pinched, or dragged against tractor parts.

8 / 40

Which of the following answers lists the three types of emergency equipment you must have on your bus?

9 / 40

Overhead inside mirror is used to:

10 / 40

Which of the following hazard classes utilizes a transport index in order to determine how much of it can be loaded on a single vehicle for transport?

11 / 40

A driver of a tanker should use an escape ramp when _____.

12 / 40

Tires should should be replaced:

13 / 40

This object should be clean with no obstructions, illegal stickers or damage to the glass.

14 / 40

As the driver of a bus, how can you best avoid hindering other traffic on the highway?

15 / 40

When would you lock some emergency roof hatches in a partly open position?

16 / 40

Which of the following is a necessary qualification for non-bulk packaging?

17 / 40

The longest crack that brake or disc drums can have is:

18 / 40

When does stab braking occur?

19 / 40

A portable tank differs from a cargo tank in that ______.

20 / 40

Why should you test the tractor protection valve?

21 / 40

To test the security of the tractor semi trailer connection you should:

22 / 40

Before transporting a sealed load, you must check:

23 / 40

What should you hear when you have the hand valve on and are testing the trailer brakes by opening the service air line at the back of the trailer?

24 / 40

Your vehicle is going down a long hill and your brakes begin to fail. What should you do?

25 / 40

Which of the following statements about overhead space is true?

26 / 40

The 3 parts of the air brake system are: service brakes, parking brakes, and ____.

27 / 40

What keeps air in the tanks should the air compressor develop a leak?

28 / 40

Select the true statement in regards to unhooking the pintle hook while the converter dolly is still under the trailer.

29 / 40

Students exit the bus and walk:

30 / 40

When should you check your mirrors for a lane change?

31 / 40

Select the action that is not recommended when driving on slippery roads:

32 / 40

You should brake on a long steep downgrade hill as a supplement to the braking effects of the engine

33 / 40

Select the statement that is true in regards to quick steering movements and triple/double trailers:

34 / 40

How do you determine if slack adjusters need to be adjusted?

35 / 40

In the event of an accident you should remember to do the following EXCEPT:

36 / 40

Carry-on baggage cannot be stored:

37 / 40

Select the false statement about suspension:

38 / 40

Which trailer should be the first one after the tractor?

39 / 40

Select the true statement in regards to converter dollies:

40 / 40

The most important hand signal you should agree on with a helper is:

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CDL Category Practice Tests

CDL Practice Test

How To Get An iowa Commercial Drivers License

Individuals may apply for their CDL starting at age 18. To be eligible for interstate driving as well as HazMat and Doubles/Triples applicants must be 21 years of age or older. All individuals applying for an Iown CDL must present a Medical Examiner’s Certificate according to the United States Federal Regulations.

If any one of the descriptions below is true about an applicant, they will be disqualified from receiving their CDL.

  • Driver posses more than one driver’s license.
  • Driver was convicted of driving under the influence in the past 24 months.
  • Driver has a suspended, denied, canceled, or revoked driver’s license.

H – Hazardous Materials
N – Tank Vehicle
T – Doubles/Triples
X – Hazmat and Tank Comb
P – Passenger Vehicle
S – School Bus

Drivers must take a knowledge test as well as a practical skills test to showcase their knowledge of commercial driving laws and their ability to operate a commercial vehicle.

Hit the Open Road

iowa CDL License Test Tips

Applicants must complete a general knowledge test to display their understanding of commercial driving laws. The general knowledge exam is comprised of 50 questions. Those seeking a Class A CDL will need to complete an additional 20 question test on combination vehicles. Applicants seeking additional endorsements will need to take an additional test on the endorsement topic. The Passenger, Tank, and Doubles/Triples Endorsements are 20 question tests. Removing the Air Brake Restriction, the Iowa Operator and School Bus Endorsements are 25 questions. The Hazmat Endorsement is a 30 question test. All applicants must pass the respective assessments with a score of 80 percent or better to receive their Iowa CDL permit.

A skills assessment is required of all applicants. This assessment is comprised of three parts, which are the pre-trip inspection, basic controls skills, and on-road driving. Individuals applying for their P and S endorsements will be required to take the skills test in the respective vehicle for their endorsement.

Additional Information

Information on the Iowa Department of Transportation

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


Phone:  515.239.1101


Additional Iowa CDL Helpful Links

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