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

This should have no illegal stickers, dirt, obstructions, or damage to the glass.

2 / 40

You must have placards for explosives, poison gas or flammables exceeding:

3 / 40

You need to raise the landing gear just to the height of where it clears the pavement before driving.

4 / 40

The front trailer supports should be____before driving away.

5 / 40

The _____of the kingpin has the locking jaw close around it.

6 / 40

A bus has a GVWR of 22,000 pounds and seats 24 passengers. What CDL class is this vehicle?

7 / 40

To find out if a shipment includes a hazardous material, you should:

8 / 40

Is it mandatory that all vehicles with air brakes have low air pressure warning signals?

9 / 40

When should air tanks be drained?

10 / 40

Be careful to check the_____when unloading the smaller tanks of bulk heads.

11 / 40

You should check the_____when loading small tanks equipped with bulkheads.

12 / 40

For emergency braking to avoid a crash when driving a double trailer you should:

13 / 40

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

14 / 40

The air leakage rate for combination vehicles should not be more than _ psi a minute.

15 / 40

Select the situation in which you should use the hand valve to park a combination vehicle.

16 / 40

Is this statement true or false: You do not need to use the parking brake if are leaving your vehicle for a short amount of time.

17 / 40

What does the service brake system do?

18 / 40

Select the true statement in regards to driving a truck with triple or double trailers:

19 / 40

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

20 / 40

Drivers placard their vehicle to _____ the risk.

21 / 40

A tank trailer should never be fully loaded due to:

22 / 40

The trailer height is correct for connecting a converter dolly to a second trailer when:

23 / 40

If you are traveling at 55 mph in a 30-foot vehicle, you should leave how many seconds of following distance?

24 / 40

Select the true statement in regards to handing triples and doubles

25 / 40

Select the true statement about emergency steering and tankers:

26 / 40

These tires should have a minimum tread depth of 4/32 inches.

27 / 40

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

28 / 40

A placarded vehicle must carry what type of fire extinguisher?

29 / 40

With most hazardous materials, you may park within 5 feet of the road briefly, if your work requires it. The materials that are the exception and do not allow parking this close to the road are:

30 / 40

What should you do before you begin to couple?

31 / 40

Animals and human foodstuffs should not be loaded in the same vehicle with?

32 / 40

The purpose for the emergency air line is:

33 / 40

Which of the following are some suspension system defects?

34 / 40

Unless you_____you will feel the effects of a liquid surge.

35 / 40

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

36 / 40

The most dangerous time during the school bus ride is:

37 / 40

How do you hook a combination to a second trailer without spring brakes and without using wheel chocks?

38 / 40

What are some things you should check on the front of your vehicle when doing the walk-around inspection?

39 / 40

Why do air brakes take longer to stop than hydraulic brakes?

40 / 40

When stopping for railroad tracks, you must stop no closer than how many feet before the nearest track?

Your score is

The average score is 62%

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.