- Updated for January 2025
- Based on 2025 CA commercial driver's license manual
Free California CDL Combination Practice Test 2025
To drive semi-trucks or tractor-trailers in California, you must obtain a Class A Commercial Driver’s License (CDL), which will allow you to drive any combination of vehicles in which the towed unit has a gross vehicle weight (GVW) or gross vehicle weight rating (GVWR) of over 10,000 pounds.
To practice commercial driving under supervision in pursuit of a CDL, you must obtain a Commercial Learner’s Permit (CLP). But to practice driving tractor-trailers, you must also pass the Combination Vehicles knowledge test. This specialized test will assess how much you know about the theory of operating combination vehicles (such as tractor-trailers). If you haven’t passed the Combination Vehicles knowledge test by the time you obtain a Class A CDL, the CDL will include a restriction prohibiting you from driving combination vehicles.
Have you been studying the official California Commercial Driver Handbook (California CDL Handbook 2025)? You certainly should do so because the questions on both the General Knowledge test and the Combination knowledge test are based on this study guide. However, you’re probably here because you want to get a little more help to pass the Combination Vehicles knowledge test than you’re getting from this handbook. We can help, just as we’ve helped thousands of other aspiring drivers.
This free California CDL Combination practice test is based on the official state manual, just like the official knowledge test. It’s up to date as of January, 2025. There are 30 multiple-choice questions and answers on such topics as combination air brake systems, coupling and uncoupling, and pre-trip inspections. Unlike the official knowledge test, this practice test comes with our automated assistant. It can give you a hint if you get stuck on a question and an explanation of the correct answer if you still miss the question.
California can offer numerous economic opportunities to tractor-trailer drivers because of its diverse economy, the largest in the United States. Economic opportunities exist in intermodal transportation at California’s ports and rail hubs, transportation of agricultural products from the Central Valley, transportation of retailers’ products through their distribution networks, and cross-border trade with Mexico.
The most important trucking route is Interstate 5, which runs from the Mexican border in California to the Canadian border in Washington State. Other important Interstate routes include Interstate 10, which is used to transport cargo to Arizona and Texas; Interstate 80, which is used to transport goods from San Francisco eastward; and Interstate 15, for moving cargo from California to Nevada. U.S. Route 101 is an alternative to I-5 for moving goods along the coast.
Routes serving the Central Valley include State Routes 58, 99, and 152.
- 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 CA DMV exam
questions
correct answers to pass
passing score
Helpful links
List of questions (classic view)
- To prevent a rollover while driving a combination vehicle, the two most important things are
- Which of the following is most likely to roll over?
- To straighten out a jackknifing trailer, should you apply your hand brake?
- Which of the following is the definition of "offtracking?"
- Which of the following should you do if you want to back into a curved path on the driver's side?
- Which of the following types of vehicle gets stuck on railroad crossings?
- If you use the trailer hand valve while driving,
- What does the trailer air supply control do?
- Which of the following controls air in the service line?
- Which of the following is NOT a purpose of the emergency air line?
- When parking a vehicle that does not have spring brakes, you should use chocks
- Where would you find the shut-off valves?
- Which of the following could happen if you try to couple when the trailer is too high?
- After coupling, how much space should there be between the lower and upper fifth wheel?
- Which of the following is NOT part of inspecting the coupling?
- To drive, how high do you need to raise the landing gear?
- Which of the following is NOT a way to tell if your trailer is equipped with an antilock braking system (ABS)?
- While uncoupling, what should you do AFTER you unlock the fifth wheel?
- Which of the following is NOT part of checking that air is flowing to all trailers?
- During a walkaround inspection of a combination vehicle, you should check to make sure that
- Which of the following is NOT part of testing the tractor protection valve?
- What is the best way to test the trailer service brakes?
- During the coupling process, you have now locked the trailer onto the tractor and secured the vehicle. When you check the lower fifth wheel, you do NOT need to check
- Which of the following is NOT true about an antilock braking system (ABS)?
- What is the first step in coupling a tractor-semitrailer?
- 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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