CDL Doubles/Triples Practice Test 2026: What to Expect
By Rish P · September 21, 2026 · Updated November 3, 2026
The doubles/triples (T) endorsement authorizes you to pull two or three trailers, and it requires passing a knowledge test but not Entry-Level Driver Training (ELDT). The test is usually about 20 questions with an 80% passing score. You'll need a Class A CDL to use it, and first-time Class A applicants can complete the required theory online with our FMCSA-registered Class A ELDT theory course.
Who needs it and is ELDT required?
You need the T endorsement to pull more than one trailer, common in LTL (less-than-truckload) freight. Like the tanker endorsement, doubles/triples is not on the ELDT list, so there is no federal training requirement, only a knowledge test. That makes it a fast, inexpensive endorsement to add.
What the test covers
Questions focus on the added risks of multiple trailers: coupling and uncoupling doubles and triples in the correct order, inspecting converter dollies and the extra connections, managing the crack-the-whip effect, and the greater care needed in braking, turning, and lane changes with a longer, less stable combination.
Sample questions
- The "crack-the-whip" effect means:
- a) The tractor swings wide
- b) The rear trailer swings with more force and speed than the tractor
- c) The brakes lock
- d) The load shifts forward
- When coupling doubles, the more heavily loaded trailer should be:
- a) In the rear
- b) Directly behind the tractor (first)
- c) It does not matter
- d) On a dolly
- A converter dolly is used to:
- a) Store cargo
- b) Connect a second or third trailer
- c) Brake the vehicle
- d) Inspect tires
- Because of the crack-the-whip effect, doubles and triples are more likely to roll over when:
- a) Parked
- b) Driven at safe speeds
- c) Turned or steered quickly at higher speeds
- d) Loaded evenly
Answers: 1) b. 2) b, the more heavily loaded trailer goes first. 3) b. 4) c.
How to pass
Study the doubles and triples section of your CDL manual, focusing on coupling order and the crack-the-whip effect, then take practice tests until you are consistently above 80%. Because there is no ELDT requirement, passing the knowledge test is the main hurdle.
The bottom line
Doubles/triples is a knowledge-test-only endorsement, no ELDT needed. Learn the coupling order and respect the crack-the-whip effect, and it is one of the quicker endorsements to add to your CDL.
Sources
Checked November 2, 2026.
- eCFR: 49 CFR 383.93, Endorsements: The doubles/triples (T) endorsement authorizes pulling two or three trailers and requires a knowledge test.
- FMCSA: Entry-Level Driver Training (ELDT): Doubles/triples requires a knowledge test but not Entry-Level Driver Training (ELDT).
- eCFR: 49 CFR 383.135, Passing knowledge and skills tests: Applicants must answer at least 80% of knowledge test questions correctly to pass.
- eCFR: 49 CFR 380.609, General entry-level driver training requirements: Doubles/triples is not on the ELDT list, so there is no federal training requirement for it.
Frequently asked questions
What is the doubles/triples endorsement on a CDL?
The doubles/triples (T) endorsement on a CDL authorizes you to pull two or three trailers behind a tractor. It requires passing a knowledge test but not Entry-Level Driver Training (ELDT). Drivers commonly use it in LTL, or less-than-truckload, freight, and you need a Class A CDL to use it.
Do I need ELDT to get a doubles/triples endorsement?
No, you do not need ELDT to get a doubles/triples endorsement. Federal ELDT rules cover Class A and B CDLs and the passenger, school bus and hazmat endorsements, so doubles/triples, like tanker, requires only a knowledge test. First-time Class A applicants still need ELDT for the Class A CDL itself.
How many questions are on the CDL doubles/triples test and what score do I need?
Most states use about 20 questions on the doubles/triples test, and you must answer at least 80% correctly to pass. The federal minimum passing score on each knowledge test is 80%, but the exact number of questions varies by state. Check your state CDL manual or DMV for the exact test format.
Can I get a doubles/triples endorsement with a Class B CDL?
No, you need a Class A CDL to use the doubles/triples endorsement, so a Class B license will not let you pull multiple trailers this way. Get your Class A first, which includes ELDT for first-time Class A applicants, then add the T endorsement by passing the knowledge test.
What is the crack-the-whip effect with doubles and triples?
The crack-the-whip effect is when the rear trailer swings with more force and speed than the tractor during a turn or quick steering change. It makes doubles and triples more likely to roll over at higher speeds. Test questions focus on it, so slow down for turns and avoid sudden lane changes.
How do I pass the CDL doubles and triples test?
Study the doubles and triples section of your state CDL manual, focus on coupling order and the crack-the-whip effect, and take practice tests until you score consistently above 80%. Because there is no ELDT requirement, the knowledge test is the main hurdle. Remember that the more heavily loaded trailer goes directly behind the tractor.
Ready to knock out your ELDT theory?
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