Tire building drum and method for turning-up a tire component

A tire building drum comprising:

• a drum body that is rotatable about a drum axis;
• an inflatable turn-up bladder extending in a circumferential direction about the drum axis around the drum body for turning-up a tire component supported on said turn-up bladder;
• a plurality of pressing arms distributed in the circumferential direction around the drum body and located between the drum body and the turn-up bladder for pressing against the turn-up bladder during the turning-up of the tire component;
• and
• a plurality of hinges for hingably connecting the pressing arms to the drum body, wherein the plurality of hinges is located underneath the turn-up bladder when the turn-up bladder is uninflated,
• wherein the tire building drum is provided with an underlay sliding over the pressing arms and extending between at least one hinge of the plurality of hinges and the turn-up bladder in a radial direction perpendicular to the drum axis, and
• wherein the underlay comprises an underlay body that is annular at a first end and split into a plurality of arm sections at a second end opposite to the first end.