A tire changing machine having a support frame, rotatable supporting device for a wheel rim, locking device for securing the wheel rim to the supporting device, a fitting tool which can be secured to an adjustable tool supporting arm carried by the support frame, and driving device for the rotatatable supporting device. The machine also includes a first and a second pressure members which can be located in diametrically opposite positions with respect to a wheel rim carried by the supporting device and are designed to act on either side of a tire on the wheel rim, and drive device for actuating, upon control, each of the first and second pressure members.