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Free IA CDL Double/Triple Trailers Practice Test 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 March 2025

Iowa’s agriculture, manufacturing, and logistics sectors depend heavily on trucks for freight transportation. I-35, I-80, and I-380 all support double-trailer trucks. In addition to double-pup trailers (which are allowed nationwide), Iowa also allows Turnpike Double (two full-size trailers) and Rocky Mountain Double (a full-size trailer followed by a pup trailer) truck configurations on designated routes. (Triple trailers are not allowed in Iowa.)

Here are some examples: Cargill, ADM, and CHS Inc. use double grain trailers to move corn and soybeans from farms to processing plants. POET Bioprocessing and Valero Renewables use double tankers for ethanol shipments. John Deere and Vermeer Corporation transport agricultural and construction equipment on double flatbed trailers. Freight companies use Turnpike Doubles and Rocky Mountain Doubles to transport goods between Chicago, Omaha, and Des Moines. UPS and FedEx Ground use double pup trailers for regional package delivery.

If you want to pull doubles or triples, you must obtain a Double/Triple (T) endorsement on your Class A CDL. For this endorsement (assuming you are already qualified to drive combination vehicles), you must pass the official Double/Triple knowledge test (but no additional skills test). This test covers such topics as safe handling, air and electrical lines, coupling and uncoupling, rollovers, and trailer sway.

This knowledge test is based on the official Iowa CDL manual (Iowa CDL Handbook 2025), especially Chapter 7: Doubles and Triples. (You likely studied other parts of this manual to pass your General Knowledge and Combination exams.)

We offer a set of tools to complement the official manual with intensive training. This is the first of our five Iowa Doubles and Triples Endorsement Practice Tests. This practice test is based on the official CDL manual, just like the official Double/Triple knowledge test. It’s up to date as of March, 2025. The 20 multiple-choice practice questions and answers on this practice test address such topics as air lines, converter dollies, coupling, following distance, rearward amplification, and rollovers.

Our AI Assistant can help you answer any practice question. It can give you a hint or an example or answer any of your own questions about driving. If you still miss the question, the AI Assistant will immediately provide you with the correct answer and an explanation. You won’t have to wait till the end of the test to get this information.

This practice test has no time limit; take all the time you need to learn and master the material covered by this practice test. You can retake this practice test as often as you wish until you’ve mastered the material.

6 min to complete

Available in EN and ES

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Helpful links

IA DMV website

Official Iowa CDL manual (2025)

More IA DOT Written Exam Resources

IA CDL Double/Triple Trailers Test (you are here)

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Written by Andrei Zakhareuski Updated over a week ago

At Driving-Tests.org, we understand the importance of reliable and accurate practice tests to help you prepare for your DMV exam. That's why we've developed a meticulous process to create and continually update our practice questions, ensuring they reflect the most current driving laws and regulations.

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FREE IA CDL Double/Triple Trailers Practice Test

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