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CDL · Pulling Doubles and Triples

What is the maximum length allowed for a twin 28-foot trailer doubles combination in most states?

Correct answer

65 feet

  1. A 60 feet
  2. B 65 feet
  3. C 70 feet
  4. D 80 feet

Why this is the answer

The most common doubles combination is two 28-foot trailers (a 'twin-28' or 'pup' combination), which totals approximately 65 feet from the front of the tractor to the rear of the last trailer. Federal law (STAA 1982) grandfathered these combinations on the Interstate highway system. Some states allow longer LCV (Long Combination Vehicle) combinations on specific routes with special permits — these require additional LCV endorsements and training beyond the standard doubles/triples endorsement.
Source: FMCSA CDL Manual, Chapter 7, Doubles and Triples, Vehicle Dimensions

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