The present invention relates to a pneumatic device for seating tire beads on the rim portions of a wheel of a vehicle. The device includes a header attached to the rotating table of a tire changing machine and which supports a wheel and a tire assembly. A plurality of upwardly extending conduits direct air from the header to the interface between a bead of a tire and the corresponding rim portion of the wheel which are adjacent the top surface of the table. The pneumatic device also includes a system for immobilizing the table during the operation of the device for seating tire beads.