A tire changer which comprises a mounting device for receiving at least a wheel rim of a wheel/tire assembly, wherein the mounting device has an axis (S), a roller which is able to contact a peripheral surface of the wheel/tire assembly and to apply a predetermined force to the peripheral surface of the wheel/tire assembly, a control device for controlling the predetermined force applied by the during a rotation of the wheel/tire assembly about the axis (S) of the mounting device and a sensor device for measuring force variations acting between the peripheral surface of the wheel/tire assembly and the roller, wherein supports of the roller and of the mounting device are designed for a relative movement of the roller and of the mounting device towards each other along a straight line to apply the predetermined force to the peripheral surface of the wheel/tire assembly.