Tyre having a tread comprising a central portion astride an equatorial plane (X-X) and two shoulder portions (L2,L3), wherein: the shoulder portions (L2;L3) each have at least one row of shoulder blocks (13;14) comprising a plurality of shoulder blocks (22;27); the central portion has at least one first and one second central rows of central blocks comprising a plurality of central blocks (32;33) and at least one first and one second lateral rows of lateral blocks comprising a plurality of lateral blocks (34;35); the central blocks (32;33) of the first and second central rows (9;10) have an average width 11 smaller than 15% of the total width L of the tread; the central blocks (32;33) of the first and second central rows (9;10) are longitudinally separated respectively by first transverse grooves (16;17); the central blocks of the first central row are axially separated from the central blocks of the second central row by a first circumferential groove with a "zig-zagging" course comprising a plurality of first inclined segments alternated with a plurality of second segments counter-inclined with respect to said first inclined segments; said first circumferential groove has a width smaller than 3 mm and a depth greater than 10 mm; said first inclined segments and said second counter-inclined segments define on each central block of the first and second central rows a first inclined side and a second side counter-inclined with respect to said first side, said first side and said second side being adapted to form a convex portion of said central block; each central block of the first central row is arranged with respect to the central blocks of the second central row so that a first side thereof faces a second side of a first central block of the second central row, and that a second side thereof faces a first side of a second central block of the second central row, distinct from said first block of the second central row; said tyre being characterized in that the lateral blocks (34;35) are circumferentially separated by second transverse grooves (18; 19) having a width that varies as a function of the depth. the shoulder portions (L2;L3) each have at least one row of shoulder blocks (13;14) comprising a plurality of shoulder blocks (22;27); the central portion has at least one first and one second central rows of central blocks comprising a plurality of central blocks (32;33) and at least one first and one second lateral rows of lateral blocks comprising a plurality of lateral blocks (34;35); the central blocks (32;33) of the first and second central rows (9;10) have an average width 11 smaller than 15% of the total width L of the tread; the central blocks (32;33) of the first and second central rows (9;10) are longitudinally separated respectively by first transverse grooves (16;17); the central blocks of the first central row are axially separated from the central blocks of the second central row by a first circumferential groove with a "zig-zagging" course comprising a plurality of first inclined segments alternated with a plurality of second segments counter-inclined with respect to said first inclined segments; said first circumferential groove has a width smaller than 3 mm and a depth greater than 10 mm; said first inclined segments and said second counter-inclined segments define on each central block of the first and second central rows a first inclined side and a second side counter-inclined with respect to said first side, said first side and said second side being adapted to form a convex portion of said central block; each central block of the first central row is arranged with respect to the central blocks of the second central row so that a first side thereof faces a second side of a first central block of the second central row, and that a second side thereof faces a first side of a second central block of the second central row, distinct from said first block of the second central row; said tyre being characterized in that the lateral blocks (34;35) are circumferentially separated by second transverse grooves (18; 19) having a width that varies as a function of the depth.