"Method of computing distance between axles for bridge formula calculations. Typically measured from center of axle to center of axle between outermost wheel or wheel cluster."
Glossary of Terms, Compilation of Existing State Truck Size and Weight Limit Laws — FHWA, May 2015. Public domain.
Axle spacing is why a gross-weight-only check cannot answer whether a rig is legal. A legal 80,000 lb five-axle van and an illegal 80,000 lb three-axle dump truck weigh exactly the same; the entire difference is in the spacing. It is also why a permit application asks for the layout rather than just the total, and why no calculator can honestly infer the spacing from a weight.
Need a Axle Spacing carrier?
QuoteFleet lists FMCSA-verified drayage and intermodal carriers, and gives shippers an instant freight quote. Find a carrier or price your move now.