Tyre changing machine, particularly for large wheels, comprising: - at least one holding frame on the ground; - gripping and rotational means associated with the holding frame, adapted to grip at least one wheel, provided with at least one rim and with at least one tyre, and to move said rim in rotation around a substantially horizontal axis of rotation, said rim comprising at least a first flange element and at least a second flange element and said tyre comprising at least a first sidewall, provided with at least a first bead approachable to said first flange element, and at least a second sidewall, provided with at least a second bead approachable to said second flange element; - lifting/lowering means of said gripping and rotational means along a substantially vertical lifting/lowering direction, said lifting/lowering means being associated with said holding frame; - at least a first bead-breaking assembly adapted to break said first bead when mounted on said rim and associated in a sliding manner with said holding frame along at least one substantially horizontal direction of sliding; and - at least a second bead-breaking assembly adapted to break said second bead when mounted on said rim, associated in a movable manner with said holding frame and alternatively positionable in at least a first work configuration, wherein it is positioned at said second bead, and in at least a second work configuration, wherein it is positioned at said first bead is located and is adapted to exert a thrust on said tyre along a direction of thrust substantially parallel to said axis of rotation; wherein: - said gripping and rotational means are adapted to define at least one working plane of said tyre changing machine, said working plane being substantially perpendicular to said axis of rotation and being splittable into at least one lower half-plane, positioned inferiorly to said axis of rotation, and into at least one upper half-plane positioned superiorly to said axis of rotation; - said first bead-breaking assembly is positioned at said upper half-plane and said second bead-breaking assembly is positioned at said lower half-plane, said bead-breaking assemblies (27, 34) being mutually staggered by a staggering angle (α) ranging between 90° and 180°; characterized by the fact that it comprises movement means of said second bead-breaking assembly along at least one substantially vertical direction of movement, said movement means being associated with said holding frame. - at least one holding frame on the ground; - gripping and rotational means associated with the holding frame, adapted to grip at least one wheel, provided with at least one rim and with at least one tyre, and to move said rim in rotation around a substantially horizontal axis of rotation, said rim comprising at least a first flange element and at least a second flange element and said tyre comprising at least a first sidewall, provided with at least a first bead approachable to said first flange element, and at least a second sidewall, provided with at least a second bead approachable to said second flange element; - lifting/lowering means of said gripping and rotational means along a substantially vertical lifting/lowering direction, said lifting/lowering means being associated with said holding frame; - at least a first bead-breaking assembly adapted to break said first bead when mounted on said rim and associated in a sliding manner with said holding frame along at least one substantially horizontal direction of sliding; and - at least a second bead-breaking assembly adapted to break said second bead when mounted on said rim, associated in a movable manner with said holding frame and alternatively positionable in at least a first work configuration, wherein it is positioned at said second bead, and in at least a second work configuration, wherein it is positioned at said first bead is located and is adapted to exert a thrust on said tyre along a direction of thrust substantially parallel to said axis of rotation; - said gripping and rotational means are adapted to define at least one working plane of said tyre changing machine, said working plane being substantially perpendicular to said axis of rotation and being splittable into at least one lower half-plane, positioned inferiorly to said axis of rotation, and into at least one upper half-plane positioned superiorly to said axis of rotation; - said first bead-breaking assembly is positioned at said upper half-plane and said second bead-breaking assembly is positioned at said lower half-plane, said bead-breaking assemblies (27, 34) being mutually staggered by a staggering angle (α) ranging between 90° and 180°;