Abstract: A method for determining a total weight supported by the suspension system of a vehicle in motion starts by obtaining information sufficient to calculate a representative value of a spring constant for the suspension system of the vehicle. Measures are then obtained of the vertical acceleration of the center of mass of the vehicle over a period of time, and these are analyzed to identify a frequency of vertical oscillation of the vehicle. This frequency, together with the spring information, is used to determine an estimate of the total weight supported by the suspension system of the vehicle. Preferably, the measure of vertical acceleration is obtained by processing outputs of at least three motion sensors attached to the vehicle. In one embodiment, the motion sensors include one linear sensor deployed to measure vertical motion information for a part of the vehicle and two angular sensors deployed to measure pitch and roll information for the vehicle.