Tyre comprising a tread , said tread comprising at least one series of rubber blocks (13 i-1 , 13 i , 13 i+1 , 13 i+2 ) delimited pairwise by a series of sipes (14 i-1 ,14 i , 14 i+1 , 14 i+2 ,14 i+3 ), said blocks (13 i-1 , 13 i , 13 i+1 , 13 i+2 ) extending one after another in a circumferential direction (X), • each block (13 i-1 , 13 i , 13 i+1 , 13 i+2 ) of the series of rubber blocks having a circumferential length (L i-1, L, L i+1, L i+2 ), each sipe (14 i-1 ,14 i , 14 i+1 , 14 i+2 ,14 i+3 ) having a circumferential width (E i-1, E i, E i+1, E i+2, E i+3 ), • said series of rubber blocks comprises blocks belonging to at least two different classes of blocks ((13 i-1 , 13 i ); (13 i+1 , 13 i+2 )), the blocks of the one same class having a substantially identical circumferential length, the blocks of two different classes of blocks having distinct circumferential lengths, • the series of sipes comprises sipes belonging to at least two different classes of sipes ((14 i-1 ,14 i ); (14 i+1 ,14 i+2 )), the sipes of the one same class of sipes having a substantially identical circumferential width, the sipes of two different classes of sipes having distinct circumferential widths, • the blocks (13 i+1 , 13 i+2 ) belonging to the class of blocks of smallest circumferential length Cb min are delimited, at least in part, by sipes (14 i+2 ,14 i+3 ) belonging to the class of sipes of smallest circumferential width CSmin • the blocks (13 i-1 , 13 i ) belonging to the class of blocks of greatest circumferential length Cb max are delimited, at least in part, by sipes (14 i-1 ,14 i ) belonging to the class of sipes of greatest circumferential width Cs max . • characterized in that blocks belonging to the class of blocks of smallest circumferential length Cb min are delimited by two sipes belonging to the class of sipes of smallest circumferential width Cs min and/or blocks belonging to the class of blocks of greatest circumferential length Cb max are delimited by two sipes belonging to the class of sipes of greatest circumferential width Cs max . • each block (13 i-1 , 13 i , 13 i+1 , 13 i+2 ) of the series of rubber blocks having a circumferential length (L i-1, L, L i+1, L i+2 ), each sipe (14 i-1 ,14 i , 14 i+1 , 14 i+2 ,14 i+3 ) having a circumferential width (E i-1, E i, E i+1, E i+2, E i+3 ), • said series of rubber blocks comprises blocks belonging to at least two different classes of blocks ((13 i-1 , 13 i ); (13 i+1 , 13 i+2 )), the blocks of the one same class having a substantially identical circumferential length, the blocks of two different classes of blocks having distinct circumferential lengths, • the series of sipes comprises sipes belonging to at least two different classes of sipes ((14 i-1 ,14 i ); (14 i+1 ,14 i+2 )), the sipes of the one same class of sipes having a substantially identical circumferential width, the sipes of two different classes of sipes having distinct circumferential widths, • the blocks (13 i+1 , 13 i+2 ) belonging to the class of blocks of smallest circumferential length Cb min are delimited, at least in part, by sipes (14 i+2 ,14 i+3 ) belonging to the class of sipes of smallest circumferential width CSmin • the blocks (13 i-1 , 13 i ) belonging to the class of blocks of greatest circumferential length Cb max are delimited, at least in part, by sipes (14 i-1 ,14 i ) belonging to the class of sipes of greatest circumferential width Cs max . • characterized in that blocks belonging to the class of blocks of smallest circumferential length Cb min are delimited by two sipes belonging to the class of sipes of smallest circumferential width Cs min and/or blocks belonging to the class of blocks of greatest circumferential length Cb max are delimited by two sipes belonging to the class of sipes of greatest circumferential width Cs max . <EOS>