Abstract: An object of the present invention is to calculate the gross weight of a moving vehicle, such as a tractor-trailer combination, from measurements acquired exclusively on the tractor. Measurements of force and acceleration are taken from, for example, the engine and or drive shaft. A related object of this invention is to accurately measure the weight distribution on the axles or tandems of a tractor-trailer combination based on measurements taken from either tractor suspension air bags or from tractor fifth wheel load, given the gross weight of the combination. The weight distribution on the axles is determined by combining sensor information taken from the fuel tank with sensor data taken from either the vehicle air springs of the vehicle or, alternatively, from a weight sensor on the fifth wheel with a known gross weight of the vehicle. Another object of the invention is to determine gross vehicle weight, in motion, using a single digital sensor to simultaneously determine force and acceleration.