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CDL knowledge test

CDL Doubles and Triples Practice Test 2026

For the T endorsement: pulling double and triple trailers, coupling and uncoupling, inspecting doubles and triples, and checking air brakes.

30 practice questions, all written from Commercial Driver's License Manual (Version 07/20/2026 (form DMV 60A), AAMVA, Virginia DMV edition). Every answer shows the manual section it comes from. Free, no sign-up.

  • 30 questions
  • 20 per attempt
  • Pass mark: 80%
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20 questions. Passing score: 80%. No sign-up needed.

Choose how you want to practice:

Test format

Passing score At least 80% correct (49 CFR 383.135 (eCFR))
Number of questions Varies by state. Check the CDL manual from your state’s licensing agency.
Our practice test 20 questions per attempt, drawn at random from 30. Pass mark: 80%.

Topics covered

  • Coupling and uncoupling 11 questions
  • Inspecting doubles and triples 7 questions
  • Pulling double and triple trailers 7 questions
  • Doubles and triples air brake check 5 questions

Sample questions

A few questions from the set. Try to answer before opening each explanation.

  1. Sample question 1

    Why must air reach all the way to the back of a double or triple rig?

    • ASo the trailer lights get power
    • BSo the landing gear can be raised
    • CSo the dolly ABS lamp will light
    • DSo all the brakes will work
    Show answer

    Answer: D. Air has to flow through every trailer and dolly to the last trailer, or some of the brakes will not work.

    Source: Commercial Driver's License Manual, Version 07/20/2026 (form DMV 60A), section 7.4.1 Additional Air Brake Checks.

  2. Sample question 2

    In bad weather, why is there a greater chance of skids and loss of traction with double and triple bottoms?

    • AThe rear trailers have no brakes on their axles
    • BTheir tires are narrower than other truck tires
    • CThey have more length and more dead axles to pull
    • DThey have fewer axles than other combination vehicles
    Show answer

    Answer: C. The drive axles have to pull a longer rig with more unpowered axles behind them, so slippery roads and mountain driving call for extra care.

    Source: Commercial Driver's License Manual, Version 07/20/2026 (form DMV 60A), section 7.1.6 Adverse Conditions.

  3. Sample question 3

    Why should you check that the fifth wheel is not too far forward?

    • ASo the air lines can reach the glad hands without stretching
    • BSo the frame and cab do not hit the landing gear or trailer in turns
    • CSo the trailer does not sit too high on the fifth wheel
    • DSo the locking jaws can reach the head of the kingpin
    Show answer

    Answer: B. If the fifth wheel sits too far forward, parts of the tractor can strike the trailer or its landing gear when the rig turns.

    Source: Commercial Driver's License Manual, Version 07/20/2026 (form DMV 60A), section 7.3.1 Additional Checks.

  4. Sample question 4

    For a combination whose coupling method is not covered in the manual, how should you learn to couple and uncouple it?

    • ABy using the triples method for every rig
    • BBy using the tractor-semitrailer method
    • CBy asking any driver who has pulled one
    • DFrom the manufacturer and/or owner specifications
    Show answer

    Answer: D. There are too many truck-trailer and tractor-trailer types for one manual, so you follow what the maker or owner of your vehicle specifies.

    Source: Commercial Driver's License Manual, Version 07/20/2026 (form DMV 60A), section 7.2.4 Coupling and Uncoupling Other Combinations.

  5. Sample question 5

    If the tractor protection valve does not work properly and a trailer brake leak drains all the air from the tractor, what could happen?

    • AThe emergency brakes could come on, with possible loss of control
    • BThe trailer lights could stop working until the leak is fixed
    • CThe engine could shut off to save the remaining air
    • DThe service brakes would work but the parking brake would not
    Show answer

    Answer: A. A faulty tractor protection valve lets a trailer leak empty the tractor's air too, and losing that air sets the emergency brakes, which can cost you control.

    Source: Commercial Driver's License Manual, Version 07/20/2026 (form DMV 60A), section 7.4.1 Additional Air Brake Checks.

How to prepare

  • Read the matching sections of your state’s CDL manual before you practice.
  • Use practice mode first: it shows the explanation and the manual reference after each answer.
  • For every missed question, reread the whole manual section we cite.
  • Switch to exam mode when you score well above 80% without help.

More detail in our guide How to Study for the CDL Knowledge Tests.

Other CDL practice tests

Which tests you need depends on your license class and endorsements, as explained in CDL Classes, Endorsements and Restrictions Explained.

Frequently asked questions

What score do I need to pass?

Federal rules require at least 80% correct on each CDL knowledge test (49 CFR 383.135 (eCFR)).

Are these the questions on the real test?

No. Real test questions are not public. We write our own questions from the official manual, so they cover the same material but are not copies of test questions.

Is the CDL manual the same in every state?

State CDL manuals are built on the same national model manual from AAMVA, so the knowledge content is largely the same. We compared 3 state editions for this test: 30 of 30 quotes appear word for word in the same section of all of them. Your own state’s manual is the final word if anything differs.

How do you check the answers?

Each question stores the manual section (or page) and an exact quote that a script checks against the manual text, then an independent AI review answers it from that part of the manual alone. See our editorial policy. Found a mistake? Tell us.

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20 questions, pass mark 80%. Free, no sign-up.

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Sources

Questions cite the newest edition we have. We also check every quote against the other state editions of the same model manual, section by section.