Method of laying a tire belt ply on a form, using one or two transporters each having gripping assemblies, for gripping and moving the gripping sectors situated at the two longitudinal ends of a belt ply. The front and rear edges are aligned, after having determined the angular geometry of the ply edges by means of a suitable device, by independently moving at least one gripping sector of each of the front and rear areas. This method makes it possible to align edges having high curvatures and to lay a belt ply on a curved form.