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 these is a good rule for backing a straight bus?

2 / 40

Rods, connecting links, and arms from the steering box to the wheel are a part of the:

3 / 40

A disruptive passenger:

4 / 40

The safety catch for the fifth wheel locking lever must be ____ for a coupling to be complete.

5 / 40

Select the vehicle that off-tracks the most.

6 / 40

Select the true statement about emergency steering and tankers:

7 / 40

Why is it dangerous to unlock the pintle hook with the dolly still under the rear trailer?

8 / 40

What should you hook up before backing a tractor to a trailer for coupling?

9 / 40

When is it acceptable for non-hazardous materials to be described by hazard class words or identification numbers?

10 / 40

You are driving a 40 foot truck at 35 MPH, how much space (in seconds) should you keep in front of you?

11 / 40

Which of the following will confirm that you are driving with anti-lock brakes?

12 / 40

You should_____to make an emergency stop with air brakes when using the stab braking method.

13 / 40

The brake pushrod should not move more than____for manual slack adjusters.

14 / 40

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

15 / 40

Which seats must have a seat belt:

16 / 40

Which of the following is NOT an important reason to look far ahead when you are driving?

17 / 40

Select the true statement about speed and stopping distance.

18 / 40

On a drawbridge, you do not need to stop, but must slow down and make sure it's safe, when:

19 / 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?

20 / 40

To inspect the______you should pump the pedal 3 times and hold it down for 5 seconds while making sure the pedal doesn't move during those 5 seconds.

21 / 40

Under which two special conditions should you downshift?

22 / 40

How much space should there be between the lower and upper fifth wheel?

23 / 40

This item does not need to be checked during the cab check.

24 / 40

Which of the following statements about loading and unloading cargo tanks is false?

25 / 40

Why is understanding the loading and unloading procedures so critical?

26 / 40

A placard is required for a combustible liquid at?

27 / 40

When you discharge an unruly passenger, you must choose a place that is:

28 / 40

Suspension systems:

29 / 40

Water is drained from the compressed air tanks because:

30 / 40

The blind spot behind the bus could extend to how many feet?

31 / 40

What is a common cause of tire fires?

32 / 40

How do you check the coolant level?

33 / 40

Select the statement that describes how you could damage the landing gear.

34 / 40

What is a king pin?

35 / 40

If your engine runs a pump used during delivery of compressed gas, should you turn off the engine before or after unhooking hoses after delivery?

36 / 40

All standing riders must stay:

37 / 40

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

38 / 40

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

39 / 40

Upon what does the amount of liquid you can carry in a load depend?

40 / 40

While driving on a clear night with low beam headlights, you should be able to stop within:

Your score is

The average score is 82%

5/5 - (1 vote)

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.