The present application relates to a wheel balancer which includes a stationary frame, a measuring shaft mounted rotatably about a shaft axis on the stationary frame and adapted to receive coaxially a rim/tyre assembly. The wheel balancer further includes an encoder configured to determine the angular positions of the measuring shaft or of the rim/tyre assembly, a load device configured to apply a load to the periphery of the rim/tyre assembly, a first measuring device configured to measure forces resulting from an unbalance of the rotating rim/tyre assembly, a second measuring device configured to measure forces acting between the load device and the periphery of the rim/tyre assembly, and a locking device configured to keep the distance between the shaft axis and a contact portion at which the periphery of the rim/tyre assembly contacts the load device constant during the measurement of the forces acting between the load device and the periphery of the rim/tyre assembly.