A load-based tire inflation system for a heavy-duty vehicle comprises at least one source of fluid pressure, suspension structure of the heavy-duty vehicle, a tire and wheel assembly and a system to control fluid pressure in the tire and wheel assembly. The suspension structure is located between a frame member and an axle and has a condition indicative of a weight of the heavy-duty vehicle. The tire and wheel assembly is operatively mounted to the axle and is in fluid communication with the source of fluid pressure. The control system controls fluid pressure in the tire and wheel assembly in response to the condition of the suspension structure.