A tire is described which has a tread pattern provided with a large central channel (2) interposed between two continuous circumferential ribs (8), and a pair of large circumferential grooves (4) located at symmetrically opposite positions relative to the central channel (2). Also provided are transverse grooves (3) having a symmetrically converging inclined extension, the axial inclination of which increasingly grows larger towards the central channel (2). The longitudinal grooves (4) each consist of a sequence of oblique portions (4a) giving the grooves a broken-line course, so that each land portion or block (5, 6) delimited by the grooves (3, 4) has a corner (5a, 6a) projecting inwardly of the corresponding circumferential groove (4) with respect to the opposite corner (5b, 6b) of the circumferentially adjacent block.