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

Which of the following is NOT a basic step to be taken at a crash scene?

2 / 40

Select the statement that describes smooth bore tanks:

3 / 40

To avoid rollover when going through a curve, the best thing to do is:

4 / 40

Never refuel your bus:

5 / 40

Select the accurate statement in regards to rolling up the landing gear to complete the coupling process.

6 / 40

If you are driving a 100-foot truck with double trailers at 30 mph in dry conditions, how many seconds of space should there be between your truck and other vehicles?

7 / 40

What will happen right away should the service air line come apart but the emergency line is intact while driving a combination vehicle?

8 / 40

Before backing under the trailer you should______when coupling a tractor and trailer with air lines already connected.

9 / 40

Who is responsible for certifying on the bills of lading that the hazardous materials are prepared properly?

10 / 40

What is the benefit of ABS?

11 / 40

It is very important that you never smoke around which hazard classes?

12 / 40

Five hazard classes that require placarding in any amount are ______.

13 / 40

This object is not checked at the rear of the trailer.

14 / 40

On a bus, you may sometimes haul small-arms ammunition, emergency shipments of drugs, or hospital supplies. The total weight of all such hazardous materials must not be greater than:

15 / 40

At what "cut out" level does the governor stop pumping air?

16 / 40

Select the statement of what you should not do if you are required to drive through flowing water or deep puddles.

17 / 40

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

18 / 40

Remember to_____to prevent rollovers.

19 / 40

It is good practice to_____when uncoupling.

20 / 40

What type fire extinguisher is required in the power unit of a placarded vehicle?

21 / 40

Which of the following statements about overhead space is true?

22 / 40

The floor liner for explosives may not:

23 / 40

Your rig should be parked on__to uncouple double trailers.

24 / 40

How can you determine if your vehicle is equipped with ABS?

25 / 40

Which of the following types of cargo must never be carried on a bus with passengers?

26 / 40

Which of the following about the front tires on a commercial bus is true?

27 / 40

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

28 / 40

Which of the following is a reason that shippers package material?

29 / 40

What gauge on the dashboard indicates electrical system charging rate?

30 / 40

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

31 / 40

Do you need to stop before a railroad crossing if you are hauling 100 pounds of Division 4.3 Dangerous When Wet material?

32 / 40

You should check your tires every ____ or every ____ when driving in very hot weather.

33 / 40

When driving with multiple trailers, which one should be right behind the tractor?

34 / 40

How often should you check the tires on a placarded trailer that has dual tires?

35 / 40

The school bus driver may be the only contact person from school system some parents meet. The percentage of such parents is as high as:

36 / 40

Why is the proper adjustment and use of all mirrors so vital to the safe operation of the school bus?

37 / 40

At around____the governor allows the air compressor to start pumping again:

38 / 40

If you are carrying Division 1.2 or 1.3 materials, how far away must you park from the traveled portion of the roadway?

39 / 40

Select how you would check the truck's slack adjusters.

40 / 40

The bus driver must accept responsibility for supervising and controlling students while on the bus route. Who is the person in charge?

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The average score is 55%

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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.