Idaho Doubles & Triples (T) Practice Test
The endorsement for pulling two or three trailers. The test targets what changes when you add trailers: the crack-the-whip effect that amplifies every steering input at the last trailer, why the lightest trailer belongs in the rear, converter dollies and how coupling doubles differs from coupling a single, and the longer gaps and slower decisions that stability demands. It's knowledge-test-only — there's no separate skills test — but several states won't let you pull triples at all, so where you can use it depends on where you drive.
Who needs it: LTL linehaul and turnpike drivers pulling sets. Knowledge test only — no separate skills exam.
Sample practice questions
The antilock braking system (ABS) is designed to:
Answer: Keep wheels from locking up so you keep steering control during hard braking — ABS prevents wheel lockup and helps you keep control; it does not by itself shorten normal stopping distance.
Keeping cargo as low as possible helps because it:
Answer: Lowers the center of gravity and makes the trailer harder to roll — A low center of gravity resists rollover; a high, top-heavy load tips easily.
After backing the dolly under the rear trailer, you should raise the rear trailer's landing gear:
Answer: Slightly off the ground so the trailer isn't damaged if it moves — Raise it just slightly during coupling to prevent damage if the trailer shifts.
Common mistakes on the Doubles/Triples test
- Putting the heaviest trailer in the rear — the test (and physics) wants it behind the tractor
- Forgetting the dolly coupling sequence and the extra air-line connections doubles require
- Ignoring rearward amplification — the last trailer can flip from an input the tractor barely felt
- Assuming triples are legal everywhere — several states prohibit them entirely
The Doubles & Triples (T) endorsement has no federal ELDT requirement — it's a knowledge test only, so practice is the whole game.
Official source: Idaho Transportation Department
CDL licensing in Idaho is administered by the Idaho Transportation Department. Fees, scheduling, forms, and the official Idaho CDL manual live on the official site: Idaho ITD — official CDL page (verified 2026-08-09).
Truckcess is not affiliated with or endorsed by the Idaho Transportation Department. Our practice tests cover the federal CDL knowledge standards (49 CFR Part 383) that every state exam is built on; exact question counts, fees, and procedures vary by state and change over time — the official site is always the authority.
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Full prep courses are one-time from $59 with 12 months of access — mytruckcess.com/cdl.
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