Patent ID: 7874333

Claim:
A tread for tires comprising an outer surface forming a running surface of width (W) and intended to come into contact with a roadway during travel, this tread comprising a tread pattern formed by elements in relief defined by a plurality of grooves of longitudinal (circumferential on the tire) and transverse (or axial on the tire) general orientation, the grooves of longitudinal orientation comprising main grooves of depth G and secondary grooves of depth G′ less than the depth G of the main grooves, this tread pattern comprising a central part (C) and edges (B) axially on either side of the central part, said central part (C), defined axially by two grooves of longitudinal orientation, and of a width of between 0.25 and 0.5 times the width W of the tread, being provided with at least one main groove ( 2 c ) of longitudinal orientation and of average depth G, wherein two innermost grooves of the central part (C) are of depth G, each edge (B) being provided with at least two grooves of longitudinal orientation, the distribution of the longitudinal grooves from the equatorial plane towards the edges being such that the main grooves and the secondary grooves are arranged alternately, each pair of longitudinal grooves defining ribs provided with a plurality of transverse grooves of a depth equal to the depth G of the main grooves, the two innermost grooves of the central part (C) defining a single rib centered on an equatorial plane (P) of the tread, wherein the depth G′ of the secondary grooves is between 0.4 and 0.6 times the depth G of the main grooves; wherein the transverse grooves of the ribs of the central part (C) comprise over at most half of their length a connecting bridge the surface radially to the outside of which is at a distance Hc from the running surface of between 0.4 and 0.8 times the depth G of the main grooves; and wherein the transverse grooves of the ribs of each edge (B) comprise over at most half of their length a connecting bridge which prevents closure of said transverse grooves, the surface radially to the outside is at a distance Hs from the running surface which is at most equal to 0.3 times the depth G of the main grooves.