A molding element for a mold for vulcanizing a tread of a tire, comprising a base able to mold part of the tread surface of the tread and a bar able to mold a groove in the tread, the bar comprising two lateral faces extending along its length and projecting from the base and an upper face connecting the lateral faces. The molding element comprises a contact edge formed by the base and the bar, intended to come into contact with another molding element to form all or part of the vulcanizing mold, and further comprising at least one recess in the bar, which opens onto one of the lateral faces and onto the contact edge, but does not open onto the upper face of the bar.

A method of forming a tire that includes providing a mold configured to mold a tire tread and having a sipe-forming element, spaced apart inwardly from an outermost molding surface, that includes a knife edge oriented towards the outermost molding surface and a submerged void-forming portion extending from the knife edge, arranging an uncured tire tread within the mold, molding the tire tread arranged within the mold, and demolding the tire tread from the mold such that the sipe-forming element forms a sipe by the knife edge (48) lacerating a thickness of the tire tread as the sipe-forming element is pulled in a direction toward the outermost molding surface and forms a submerged void arranged below the sipe within the tire tread. A tire including a sipe (30) and a submerged void (32) as described above is also disclosed.

One embodiment of the invention includes a method for imparting a unique identifier to a molded polymeric article. The method includes providing a label comprising indicia having a thickness effective for embossing the polymeric article during molding and a melting point greater than the melting point of the molded polymeric article. The method also includes attaching the label to the article prior to vulcanization. The method further includes vulcanizing the article so that indicia emboss the molded polymeric article by forming indentations in the molded polymeric article.

A tire tread comprising: a first tread element with a first radially outermost surface, a second tread element with a second radially outermost surface, a groove between the first tread element and the second tread element. The groove comprises a first section with a side surface which is inclined with respect to the first radially outermost surface of a first inclination angle; and a second section comprising a radially outermost portion with an inclined surface which is inclined with respect to the first radially outermost surface of a second inclination angle. The latter is narrower than the first inclination angle. The first inclination angle and the second inclination angle exhibit an inclination difference ranging from 20 to 80. The second section comprises a radially innermost portion with a passage, a slit portion connecting the radially innermost portion to the radially outermost portion. The slit portion is narrower than the passage.