The present invention is relative to a method for building tyres for vehicle wheels and to a transfer device (16) of an apparatus for building tyres for vehicle wheels. The centring device (16) comprises: an annular support structure (18); gripping elements (19) arranged as a ring on the annular support structure (18) and having gripping surfaces (20) directed radially towards a longitudinal axis (Z-Z) of the transfer device (16); a measurement device (30) mounted on the annular support structure (18). The measurement device (30) is configured for detecting the centring between the transfer device (16) and a drum (12, 13) situated within the transfer device (16). The transfer device (16) is configured for picking up the tyre being processed (14, 15) from the drum (12, 13) on which the tyre being processed is arranged or for depositing a tyre being processed (14, 15) on the drum (12, 13).