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Free Iowa CDL Permit Practice Test: General Knowledge 2025

  • Perfect for first-time and renewal CDL/CLP applicants, and those adding endorsements
  • Based on 2025 IA commercial driver's license manual
  • Triple-checked for accuracy
  • Updated for July 2025

In the United States, there are three main classes of Commercial Driver’s Licenses (CDLs). A Class A CDL allows you to operate a combination vehicle with a gross combination weight rating (GCWR) of 26,001 pounds or more, provided the towed vehicle(s) has a gross vehicle weight rating (GVWR) of more than 10,000 pounds. This class of CDL is typically for operating semi-trucks and tractor-trailers. A Class B CDL allows you to operate a single vehicle with a GVWR of 26,001 pounds or more or a combination vehicle where the towed vehicle has a GVWR of 10,000 pounds or less. This class of CDL is typically for operating large buses and straight trucks, including box trucks and most dump trucks. A Class C CDL allows you to operate other kinds of commercial vehicles that transport hazardous materials or at least 16 occupants (including the driver). This class of CDL is typically for operating small buses (including shuttle buses) or small trucks carrying hazardous materials.

No matter which class of CDL you plan to get, you must meet a series of requirements. For one, you must pass an official skills test, which includes basic vehicle maneuvers, a pre-trip inspection, and a road test. To be sure of passing the skills test, you must practice commercial driving under supervision until you’re proficient. And to be allowed to practice commercial driving, you must hold a Commercial Learner’s Permit (CLP).

To obtain a CLP, you must also meet certain requirements, including passing the official General Knowledge test on the basic theory of commercial driving. The questions on this test are based on the official Iowa National CDL Manual (Iowa CDL Handbook 2025). You should read the manual a couple of times to learn as much as you can from it. But if you’ve found it tough to learn enough information from the manual, you probably need some more help.

This free Iowa CDL permit practice test is based on the official CDL manual, just like the official knowledge test. It’s up to date as of July, 2025. There are 50 multiple-choice practice questions on such topics as basic maneuvers, cargo management, emergency preparedness, and pre-trip inspections. Our automated assistant can give you a hint if you get stuck or an explanation of the correct answer if you still miss the question. There’s no time limit; take all the time you need to learn and master the material covered by this practice test.

Be sure to try our other CDL General Knowledge practice tests too.

FAQs

How can you get yours?

To obtain a CDL license in Iowa, first get a commercial learner’s permit (CLP) by passing the required knowledge tests. Hold the CLP for at least 14 days before taking the skills test. Complete CDL training (recommended) and pass the skills test. Ensure you meet all medical and legal requirements.

What is the associated cost?

The cost for a CDL in Iowa includes a $12 fee for the CLP and a $16 fee for the CDL license. Additional costs may apply for skills testing and CDL training programs.

How long does training last?

CDL training duration in Iowa varies by program. Full-time training typically ranges from a few weeks to several months, depending on the school and the specific program.

What can disqualify you from being eligible?

In Iowa, disqualifications from obtaining a CDL include serious traffic violations such as DUIs, reckless driving, criminal convictions involving motor vehicles, and failing the medical examination required for CDL holders.

How long does the test take?

The Iowa CDL permit test duration varies based on the applicant’s preparedness and test-taking pace. The general knowledge test, which is part of the permit test, typically consists of 50 questions.

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IA commercial driver's license
  • Perfect for first-time and renewal CDL/CLP applicants, and those adding endorsements
  • Triple-checked for accuracy

What you need to know

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Available in EN and ES
Verified by Steven Litvintchouk, M.S., Chief Educational Researcher, Member of ACES. See our detailed commitment to accuracy and quality in our practice tests.
Ensuring the accuracy and quality of our program is paramount. Learn more about our rigorous standards in our Commitment to Accuracy article.

What to expect on the actual IA DOT exam

50

questions

40

correct answers to pass

80%

passing score

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List of questions (classic view)

  1. Truck drivers are in an ideal position to spot and report human trafficking occurring at truck stops and rest areas. Which of the following trafficking red flags should you look for?
  2. Hazardous materials placards are
  3. How far ahead should you look while driving?
  4. If you feel drowsy while driving, what should you do?
  5. When beginning a long downgrade, which of the following should influence your choice of speed?
  6. You don't want to be a distracted driver, so you
  7. How can you determine if your vehicle is equipped with an anti-lock braking system (ABS)?
  8. If the engine is not overheated, is it completely safe to remove the radiator cap?
  9. It has just reached freezing. Which of the following areas may be slippery?
  10. Why should you cover cargo?
  11. What is the best way to figure out how many seconds of following distance you have?
  12. The minimum tread depth for front tires is
  13. During your pre-trip test, when examining hoses with the instructor, you need to look for
  14. You should keep the starter switch key in your pocket while you are performing the pre-trip inspection because
  15. If you are traveling at 55 mph in a 30-foot vehicle, you should leave how many seconds of following distance?
  16. What might happen if you swing wide to the left before you turn right?
  17. What can you do at an accident scene to help avoid another accident?
  18. Which of the following can cause a vehicle fire?
  19. An anti-lock braking system (ABS) will
  20. Which of the following is a key steering component?
  21. Signs of distracted drivers include
  22. Which of the following statements about retarders is correct?
  23. Which is NOT one of the four skill areas that operating a commercial vehicle requires?
  24. Before a trip, to prevent drowsiness, you should
  25. Always try to back toward the driver's side because
  26. When backing, it is important to use a helper
  27. Which of the following should you NOT do if you experience a tire failure?
  28. Letting the air out of hot tires
  29. What is the gross vehicle weight (GVW)?
  30. You should inspect wheel bearing seals for
  31. What is the definition of a hazard?
  32. On which of the following types of fires should you NOT use a B:C fire extinguisher?
  33. How can you start moving without rolling backward?
  34. How long does it take a typical tractor-trailer to clear a double railroad track?
  35. On wet roads, you should reduce your speed by
  36. To transport cargo safely, which of these are you NOT responsible for?
  37. Which of the following are likely to get stuck at a railroad crossing?
  38. Do empty trucks have the best braking?
  39. The most important hand signal you should agree on with a helper is
  40. Total stopping distance equals
  41. Where should you place your warning devices if you must stop on a one-way road or divided highway?
  42. Starting the engine and inspecting the cab involves each of the following tasks, EXCEPT
  43. In which of the following two situations should you downshift?
  44. Which of these is NOT part of the basic method of shifting up?
  45. Which of the following is NOT something you should check during a trip?
  46. What will help a drunk sober up?
  47. For how long will you lose your CDL driving privileges if you are convicted of a second DUI offense in a CMV?
  48. If you double your speed, how much more distance will it take to stop?
  49. How many tie-downs are required for a 20-foot load?
  50. If you are confronted by an aggressive driver, you should
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