- Updated for January 2025
- Based on 2025 IL commercial driver's license manual
Free Illinois CDL Combination Practice Test 2025
We’re glad you decided to take our free Illinois CDL Combination practice test! This practice test will help you prepare to pass the official CDL Combination Vehicles knowledge test. You should start by studying Section 6 (Combination Vehicles) of the official Illinois Commercial Driver’s License Study Guide (Illinois CDL Handbook 2025). Then by taking this practice test, you’ll absorb the relevant material and become more accustomed to being tested on it. The practice test is based on the official state CDL Study Guide, just like the official knowledge test. It’s up to date as of January, 2025 and has 30 multiple-choice questions. The questions and answers on this practice test will assess your understanding of such topics as combination braking systems, driving techniques, pre-trip inspections, and rollovers. However, this practice test differs from the official knowledge test in the extra features it provides to help you learn, including a hint and an explanation of the correct answer for each question, and an automated assistant for even more help.
There are three classes of Commercial Driver’s Licenses (CDLs): Class A, Class B, and Class C. A Class A CDL allows you to operate combination vehicles with a Gross Combination Weight Rating (GCWR) of 26,001 or more pounds, provided the Gross Vehicle Weight Rating (GVWR) of the unit being towed is over 10,000 pounds. To drive semi-trucks and tractor-trailers, this is the class of CDL you want.
All aspiring commercial drivers must pass the General Knowledge written test. But to obtain a Class A CDL and drive semi-trucks or tractor-trailers, you must also pass the Combination Vehicles knowledge test. Otherwise, your CDL will include a restriction prohibiting you from operating tractor-trailers, which would defeat the purpose of obtaining a Class A CDL. In fact, if you don’t pass that knowledge test, you won’t even be allowed to practice driving tractor-trailers.
Once you obtain a CDL and all the endorsements you need, you can start earning money as a commercial driver. Illinois (especially the Joliet/Elwood area) has one of the greatest intermodal transportation hubs in the country, including extensive rail and highway networks and airports for air freight. Illinois is a leading agricultural producer of corn, soybeans, and livestock. In addition, Illinois is also a leading manufacturing state. Major manufacturing sectors include chemicals, machinery, and food products. Truck drivers transport all these and other products.
Major trucking routes include but are not limited to Interstates 55, 57, 80, 90, and 94; U.S. Routes 20, 30, and 51; and Illinois Route 53.
- Perfect for first-time and renewal CDL/CLP applicants, and those adding endorsements
- Triple-checked for accuracy
What you need to know
What to expect on the actual IL DMV exam
questions
correct answers to pass
passing score
Helpful links
List of questions (classic view)
- What is the proper following distance for a 90-foot vehicle traveling at 50 mph?
- You do NOT need to drive slowly to avoid a rollover on
- Which of the following is NOT part of stopping a trailer skid?
- What does the crack-the-whip effect cause?
- Since what year have trucks been required to have antilock brake systems (ABS)?
- What is the proper following distance for a 60-foot vehicle traveling at 30 mph?
- What percentage of truck driver deaths in crashes are the result of truck rollovers?
- Which of the following is NOT a step in backing your trailer?
- What is the first step in coupling a tractor-semitrailer?
- Which of the following is NOT true about an antilock braking system (ABS)?
- Which of the following makes a rollover more likely?
- Which of the following off-tracks the most?
- Which of the following is NOT a part of inspecting the fifth wheel?
- Which of the following is NOT a part of raising the landing gear?
- What will happen if air doesn't flow all the way to the back?
- Which of the following are likely to get stuck at a railroad crossing?
- Which of the following is NOT part of inspecting the sliding fifth wheel?
- Compared with a regular five-axle tractor-trailer, how much more likely is the final trailer of a triple to roll over?
- What is the usual range at which the trailer air supply knob will pop out?
- Which of the following is part of securing the tractor?
- Trucks built since 1975 usually have
- What should you do if your vehicle gets stuck at a railroad crossing?
- Which of the following is NOT part of a trailer air line system?
- Which of the following is NOT part of testing the trailer's service brakes?
- If you must back along a crooked path, which side should you back toward?
- Loss of air pressure in the emergency line causes
- Which of these statements is true?
- If you cannot make a right turn without swinging into another lane, what should you do?
- If there is a major leak in the _________, the tractor protection valve will close and the trailer emergency brakes will come on.
- The rear wheels of which vehicle will off-track the most?
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