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CDL · Pulling Doubles and Triples

What is the typical maximum legal length of a doubles combination?

Correct answer

Federal law allows doubles up to 28-foot trailers each (with a typical maximum combination length around 65-75 feet); some states allow longer, including 'longer combination vehicles' under permit

  1. A Doubles combinations have no length limit
  2. B Federal law allows doubles up to 28-foot trailers each (with a typical maximum combination length around 65-75 feet); some states allow longer, including 'longer combination vehicles' under permit
  3. C 100 feet on all highways
  4. D 53 feet maximum

Why this is the answer

Federal law established a minimum federal standard for doubles: each trailer up to 28 feet (the classic 'doubles' or 'pups') and the combination at typical lengths around 65-75 feet depending on tractor and configuration. States may allow longer combinations under permits ('Longer Combination Vehicles' or LCVs), with triples, turnpike doubles, and Rocky Mountain doubles authorized in specific states (especially in the western US). LCV operations have additional driver qualification requirements and route restrictions. Driving outside legal length limits is a serious violation. Always check state-specific rules for the routes you operate on.
Source: FMCSA CDL Manual 7.0 Doubles and Triples

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