Tyre having a tread comprising a central annular portion across an equatorial plane (X-X) and two shoulder annular portions (L2, L3), located on axially opposite sides relative to the central annular portion, the central annular portion being separated from each shoulder annular portion by a respective first circumferential groove (3, 4), wherein the central annular portion comprises a plurality of blocks (20, 21), arranged in at least one circumferential row comprised between two circumferential grooves (3, 4, 5, 6, 7), and at least one sipe adapted to separate two circumferentially consecutive blocks (20, 21); each block being circumferentially delimited, by means of two consecutive sipes, by two opposite walls extending with a substantially transverse course relative to the equatorial plane (X-X) of the tyre and with a substantially radial course from the bottom of the sipe to the radially outermost surface of the block (20, 21); on at least one of the opposite transverse walls of a first block (20, 21) being present at least one first deformation (302; 303); said at least one first deformation (302, 303) defining a first constraint together with a corresponding first deformation (302, 303) present on the facing wall of a second block (20, 21) circumferentially adjacent to said first block (20, 21); said first constraint acting at least in a circumferential direction; - at least one second deformation is present on at least one of the opposite transverse walls of said first block (20, 21); - said second deformation defines a second constraint together with a corresponding second deformation present on the facing wall of said second block (20, 21) circumferentially adjacent to said first block (20, 21), said second constraint acting at least in a radial direction; - said second deformation extends at least on the said first deformation (302; 303) so that said first and second deformations are located at the same wall portion of the block; - said second deformation extends axially so as to have a course located at different radial depths of the sipe; characterised in that - said second deformation extends in a central portion on the transverse wall of the first and/or second block with an axial extension smaller than 70% of the axial extension of the transverse wall of the first and/or second block; - said second deformation circumferentially extends on said first deformation in a direction opposite to the rolling direction of the tyre; and in that - on at least one of the opposite transverse walls of said first block (20, 21) at least one third deformation is present having a depth altogether decreasing from an axial end of the transverse wall of the first block towards a central region of said transverse wall and wherein said third deformation has maximum radial extension smaller than 30% of the maximum depth (h) of the sipe; - said third deformation defines a third constraint together with a corresponding third deformation present on the facing wall of said second block (20, 21) circumferentially adjacent to said first block (20, 21), said third constraint acting at least in a radial direction. - at least one second deformation is present on at least one of the opposite transverse walls of said first block (20, 21); - said second deformation defines a second constraint together with a corresponding second deformation present on the facing wall of said second block (20, 21) circumferentially adjacent to said first block (20, 21), said second constraint acting at least in a radial direction; - said second deformation extends at least on the said first deformation (302; 303) so that said first and second deformations are located at the same wall portion of the block; - said second deformation extends axially so as to have a course located at different radial depths of the sipe; - said second deformation extends in a central portion on the transverse wall of the first and/or second block with an axial extension smaller than 70% of the axial extension of the transverse wall of the first and/or second block; - said second deformation circumferentially extends on said first deformation in a direction opposite to the rolling direction of the tyre; - on at least one of the opposite transverse walls of said first block (20, 21) at least one third deformation is present having a depth altogether decreasing from an axial end of the transverse wall of the first block towards a central region of said transverse wall and wherein said third deformation has maximum radial extension smaller than 30% of the maximum depth (h) of the sipe; - said third deformation defines a third constraint together with a corresponding third deformation present on the facing wall of said second block (20, 21) circumferentially adjacent to said first block (20, 21), said third constraint acting at least in a radial direction.