An apparatus for plotting a tread pattern on a vulcanized tire (2 ) which is mounted to a rim (7 ) rotatably supported by a primary framework (5 ) and oscillatable about two axes (Z, X) perpendicular to each other and to the axis of rotation (Y) of the tire (2 ). A signal from an electronic computer into which a base data sequence relating to a trace pattern to be reproduced on the tire is stored, is fed with a detection data sequence relating to the surface extension of said tire. The base data are processed depending on the detection data sequence for creating an application data sequence, so that, based on said application data, the electronic computer operates a laser beam emitter (10 ) carrying out plotting of the required trace pattern on the outer surface of the tire, as the sum of subsequent distinct portions, each of them being plotted, while the tire is stationary, through oscillations of the laser beam within a cone of predetermined width.