"A common vehicle dimension for governing the turning performance of tractor semitrailer combinations; typically the distance is measured from the kingpin to the center of the rear axle or rear axle group."
Glossary of Terms, Compilation of Existing State Truck Size and Weight Limit Laws — FHWA, May 2015. Public domain.
KPRA is not the trailer's length and cannot be derived from it: two 53 ft trailers with their tandems slid to different positions have the same length and different KPRA. That matters because a state can cap the trailer, cap KPRA, cap both, or cap neither — and at least one state does not cap semitrailer length at all, exempting the trailer from its single-vehicle length rule whenever KPRA is within limits. Reading a KPRA figure as a length limit would flag every ordinary 53 ft trailer in that state as over-length.
Need a Kingpin to Rear Axle carrier?
QuoteFleet lists FMCSA-verified drayage and intermodal carriers, and gives shippers an instant freight quote. Find a carrier or price your move now.