Tread including recessed channel and recessed incision and mold for tread

A tread of thickness E for a tire, said tread having a running surface, limited transversely by lateral edges, said tread being provided when new with a tread pattern comprising at least a plurality of rubber blocks arranged circumferentially on at least one of its lateral edges, said rubber blocks being separated from each other by grooves oriented virtually transversely and separated from tread pattern motifs located axially to the inside by groves oriented mainly circumferentially, when each of said plurality of blocks comprises:

• at least one recessed channel of average width at least equal to the width of the transverse grooves, each channel (1) being radially beneath the running surface, (2) having an average trace identical to the average trace of said transverse grooves, (3) forming a new groove opening radially towards the outside of the tread to divide said block into two blocks after wear of the new tread of between 15% and 45% of the thickness E of said new tread, and (4) extending within the remaining thickness of the tread;
• and
• at least one Y-shaped incision having, in radial projection on the running surface of the tread when new, a transverse orientation identical or virtually identical to that of the channel(s) projected on the same surface and each incision having small width compared with the average width of each channel, said at least one Y-shaped incision comprising a stem and two branches recessed radially towards the inside from the running surface, at least one branch being located on either side of said at least one channel, each Y-shaped incision opening radially onto the running surface at the latest at the time of the opening of the channel to form said new groove on said running surface and extending within the thickness of the tread over the entire depth of the opened channel(s).

A tread of thickness E for a tire, said tread having a running surface, limited transversely by lateral edges, said tread being provided when new with a tread pattern comprising at least a plurality of rubber blocks arranged circumferentially on at least one of its lateral edges, said rubber blocks being separated from each other by grooves oriented virtually transversely and separated from tread pattern motifs located axially to the inside by grooves oriented mainly circumferentially, wherein radially beneath the running surface each of said plurality of blocks comprises:

• at least one recessed channel of average width at least equal to the width of the transverse grooves, each recessed channel (1) having an average trace identical to the average trace of said transverse grooves, (2) forming a new groove opening radially towards the outside of the tread after wear of the new tread of between 15% and 45% of the thickness E of said new tread, (3) extending within the remaining thickness of the tread and (4) having a contour, when viewed in section, which has at least two contour parts spaced apart by a distance at least equal to half the maximum width of said channel, said parts being located radially beneath the running surface at distances less than the distances of the other points of said contour;
• and
• at least one recessed incision having, in radial projection on the running surface of the tread when new, a traverse orientation identical or virtually identical to that of the recessed channel(s) projected on the sane surface and each incision having small width compared with the average width of each channel, each incision opening radially onto the running surface at the latest at the time of the opening of the recessed channel to form said new groove on said running surface and extending within the thickness of the tread over the entire depth of the opened channel(s).

A mold for molding a tire provided with a tread extending axially via sidewalls as far as bead zones, said mold having a closed position and an open position and comprising two shells provided with molding surfaces each for molding a tire sidewall and a structure forming a ring concentric to the two shells for molding the tread of the tire, said ring and the shells, in the closed position of the mold, being in contact via their lateral ends, said mold being characterized in that:

• at least one shell is formed of at least two annular shell parts concentric to each other, such that the molding surfaces of said parts, in the closed position of the mold, mold an entire sidewall,
• at least one of the shell parts is provided with at least a plurality of elements in relief projecting onto the molding surface of said shell part, said elements in relief of the same shell part having a point of anchoring and an end axially outermost of anchoring and having virtually the same geometry and the same orientation defined as being the direction between the point of anchoring of an element on the shell part and the end of said axially outermost element of said shell part,
• each of the shell parts bearing elements in relief is mobile in the circumferential direction relative to the other parts of the same shell, so as to permit the rotation of each of said parts relative to the other parts of the same shell at least under the action of the forces exerted by the tread on the elements in relief during demolding with the aim of facilitating demolding of the tire.