CDL Combination Vehicles Practice Test 2026: What to Expect
By Rish P · September 10, 2026 · Updated November 3, 2026
The CDL combination vehicles test is a required knowledge test for a Class A CDL, the license you need to drive tractor-trailers and other combination vehicles. It is usually about 20 questions with an 80% passing score, and it is separate from the general knowledge and air brakes tests. If you're working toward a Class A, our FMCSA-registered Class A ELDT theory course covers this combination-vehicle material as part of the federal theory curriculum.
What it covers
The test focuses on the added risks of pulling a trailer: coupling and uncoupling a tractor and trailer safely, inspecting the fifth wheel and connections, trailer brakes and the trailer air supply, rollover prevention, managing the extra length in turns, and preventing trailer skids and jackknifes.
Who needs it
Only Class A applicants. If you are getting a Class B CDL to drive a single straight truck or bus, you do not take this test. If you plan to drive tractor-trailers, you do.
Sample questions
- When coupling, the fifth-wheel jaws should close around the:
- a) Air lines
- b) Kingpin
- c) Landing gear
- d) Mud flaps
- To test that the trailer is securely coupled, you should:
- a) Honk the horn
- b) Gently pull forward with the trailer brakes locked
- c) Rev the engine
- d) Check the tires
- The most likely time for a trailer to roll over is:
- a) On straight highway
- b) In curves and ramps taken too fast
- c) While parked
- d) During coupling
- Before uncoupling, you should:
- a) Lower the landing gear until it supports the trailer
- b) Leave the landing gear up
- c) Disconnect the brakes first
- d) Drive forward quickly
Answers: 1) b. 2) b. 3) b. 4) a.
How to pass
Study the combination vehicles and coupling/uncoupling sections of your CDL manual, then take practice tests until you are consistently above 80%. After your permit, you complete Class A ELDT theory and behind-the-wheel training before the skills test (49 CFR 380.609).
Sources
Checked November 2, 2026.
- eCFR: 49 CFR 383.135, Passing knowledge and skills tests: Applicants need at least 80 percent on each knowledge test, and failing the combination vehicle portion bars a Class A permit or CDL.
- eCFR: 49 CFR 383.111, Required knowledge: Combination vehicle drivers must know coupling and uncoupling, vehicle inspection, and safe operation of combination vehicles.
- eCFR: 49 CFR 380.609, General entry-level driver training requirements: Class A applicants must complete entry-level driver training before taking the skills test.
- FMCSA: Entry-Level Driver Training (ELDT): Class A ELDT includes theory and behind-the-wheel training completed before the CDL skills test.
Frequently asked questions
Do I need to take the combination vehicles test for a Class B CDL?
No, the combination vehicles knowledge test is only required for a Class A CDL. Federal rules say an applicant who fails that portion cannot be issued a Group A permit or license. If you are getting a Class B to drive a single straight truck or bus, you skip it. If you plan to drive tractor-trailers, you take it.
How many questions are on the CDL combination vehicles test and what score do I need to pass?
You need at least 80 percent correct to pass, and most tests have about 20 questions. The 80 percent passing score is the federal minimum for each knowledge test, while the exact number of questions varies by state. If you score below 80 percent, you cannot get a Class A permit or license until you retake it.
Is the combination vehicles test the same as the air brakes test?
No, they are separate tests that cover different material. The combination vehicles test covers coupling, uncoupling, inspecting and safely driving a tractor-trailer, while the air brakes test covers air brake systems. Most Class A applicants take the general knowledge, air brakes and combination vehicles tests, and each one needs at least 80 percent to pass.
What topics are on the CDL combination vehicles test?
The test covers coupling and uncoupling a tractor and semi-trailer, inspecting combination vehicles, and operating them safely. In practice that includes checking the fifth wheel and connections, trailer brakes and air supply, rollover prevention, handling the extra length in turns, and avoiding trailer skids and jackknifes. Coupling and uncoupling steps are often the hardest part, so practice those most.
What do I have to do after passing the combination vehicles test to get a Class A CDL?
After you pass your knowledge tests and get your permit, you complete Class A ELDT theory and behind-the-wheel training with a provider listed on the FMCSA Training Provider Registry. You must finish that training before you can take the skills test. Your provider reports the completion, and then you can schedule the road test for your Class A CDL.
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