T Doubles/Triples (T) Endorsement

Requirements verified July 20, 2026

The doubles/triples (T) endorsement lets you pull double or triple trailers. It's a knowledge test only, focused on the extra rollover and 'crack-the-whip' risk of pulling more than one trailer.

The doubles/triples (T) endorsement lets you pull more than one trailer at a time. It's a knowledge test only — no skills test and no background check — but the handling risks are real, so the test concentrates on them: rearward amplification (the 'crack-the-whip' effect that's strongest on the last trailer), rollover risk, managing space, and the correct order for coupling and uncoupling converter dollies and multiple trailers.

One frequently tested detail is the trailer air-supply / shut-off valve rule: the shut-off valves at the rear of a trailer must be open on every trailer except the very last one, where they must be closed. Get that wrong and the rear trailers won't have brakes.

ELDT does not apply to the doubles/triples endorsement, so there's no federally required training provider — but you'll need a Class A CDL to pull doubles or triples in the first place.

Who needs the T endorsement?

Any driver pulling double or triple trailer combinations. You need a Class A CDL to pull doubles or triples.

What it takes

Test: Knowledge test only.

Federal requirements: Pass the doubles/triples knowledge test. No skills test and no background check are required.

ELDT does not apply to the doubles/triples endorsement. The T endorsement is knowledge-only, but pulling multiple trailers greatly increases rollover and 'crack-the-whip' risk, which the test focuses on.

Doubles/Triples (T) Endorsement FAQ

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