Air pressure on a triple-trailer rig takes:
Correct. Each additional trailer adds line length. Brake response at the rear trailer of a triple is noticeably delayed — brake earlier.
CDL Practice Question #353
Category: Doubles/Triples
Why this question matters
This question is one of 50 in our Doubles/Triples bank. The reasoning above comes directly from the AAMVA CDL Manual, the source document used by every U.S. state DMV. Memorizing the underlying rule — not just the letter answer — is what separates passing on the first attempt from a return trip and another fee.