An engineering analysis of vehicle braking is presented in terms of the utilization of available road friction. Physical relations are derived which allow the determination of optimum brake force distribution on front and rear wheels as a function of axle loading. Ideal braking distribution curves are shown for a typical vehicle in the loaded and unloaded conditions. A technique is suggested for rational design of braking system parameters. It is applied to the case of a two-stage proportioning system, and is validated by experimental data from tests using a specially equipped light truck.It is concluded that a proper design analysis can establish a combination of braking system parameters which results in improved utilization of available friction. A simple, self-adjusting brake proportioning system can be a highly cost-effective safety device for truck use.