Most states specify the maximum weight they will allow on a single axle or configuration of axles. For each axle configuration, a number of states have a case-by-case calculation for the maximum weight on an axle, which varies by spacing, route, tire width, and/or the legal bridge limit. Carriers add axles in order to meet maximum weight thresholds, but more axles mean heavier total weights, lower gas mileage, higher fees for equipment use and ultimately a more expensive move. When possible, we opted to the map the permit maximums for routes within states that covered the majority of interstates or the majority of roadways.
