A device for lifting the bottom side wall (7b) of the tire (7) in a tire removing machine comprises a frame (10), an arm (16) rotatably associated with the frame (10) at a first end of it (16a) to rotate between an angular rest position and an angular working position. A supporting element (18) is connected to a second end (16b) of the arm (16) to support a bottom side wall (7b) of a tire (7) when the arm (16) is in the working position. The device also comprises an arm (16) rotation stop member (20) operatively positioned between the arm (16) and the frame (10) and able to be activated to prevent the arm (16) from turning relative to the frame (10) at least at the angular working position.