A tire building drum is disclosed. A thrust plate is mounted at a tapered end of a central shaft. An actuator is slidable along the shaft between first and second positions. Arcuate segments are arranged in a circumferential relationship about the shaft to define a working surface. First guide rails are slidably secured to the thrust plate, with a first end of each first rail mounted near a first end of one of the segments and a second end extending radially inwardly along the thrust plate. Second guide rails are slidably secured to the actuator, with a first end of each second rail mounted near a second end of one of the segments and a second end extending radially and axially inwardly along the actuator. Each of the guide rail second ends extends radially inward toward the inwardly tapered shaft portion when the actuator is in the first position.