Free practice test
CDL Combination Vehicles practice test
The free test below follows the real Combination Vehicles test: 20 questions, 16 right to pass, 20 to 25 minutes. (25 questions in some states.) Class A drivers take it, because pulling a trailer changes how a truck turns, brakes and backs.
FirstTry CDL is not affiliated with any DMV, FMCSA or government agency. Practice questions are exam-style questions built from the official CDL manual, not actual test questions.
How the Combination Vehicles test is scored
You need 16 of 20 right, which is 80%. That means you can miss 4. Class A applicants. It covers driving, braking, coupling and inspecting a tractor and trailer.
Some states differ: 25 questions in some states. Check your state's manual for its count.
What is on the Combination Vehicles test
- Driving a combination: rollover, rearward amplification, off-tracking and backing
- Combination air brakes: the trailer air supply, the tractor protection valve and glad hands
- Coupling and uncoupling, in order
- Inspecting a combination: the coupling system, fifth wheel and kingpin
What trips drivers up
Coupling steps, in order
The test asks what you do first, what you check before you back under, and how you confirm the lock. Learn the order, not just the parts.
Rearward amplification
In a quick lane change the last trailer swings out farther than the tractor. Slow down and steer gently.
Rollover
Most rollovers happen in curves and on ramps. Brake before the curve, not in it.
Off-tracking
In a turn the rear wheels follow a shorter path than the front wheels. Give yourself room.
Trailer brakes
Know what the trailer air supply does, and what happens to the trailer brakes if the trailer loses air.
Numbers come from the CDL manual and federal rules. A few differ by state or manual edition, so check your own state's manual. See our sources.
More practice tests
Common questions
How many questions are on the CDL Combination Vehicles test?
The national default is 20 questions, and you need 16 right (80%) to pass. Some states use 25 questions.
Who has to take the Combination Vehicles test?
Class A applicants. If you will pull a trailer over 10,000 lbs, plan on taking it.
Is Combination Vehicles harder than Air Brakes?
Most drivers find it easier. It is mostly about the order of the coupling steps and how a trailer changes the way you drive.
What is rearward amplification?
It is the extra swing at the back of a combination vehicle in a sudden lane change. The farther back the trailer, the bigger the swing.