A circumferential groove has a groove bottom and a pair of groove walls. Groove bottom includes groove bottom protruding portions protruding radially outwardly from a groove bottom reference surface and having a first groove bottom surface extending radially. The first groove bottom surface includes a first surface portion on one side of a center line of the circumferential groove and a second surface portion positioned on the other side, and an angle between them is 20 to 170. The groove wall includes groove wall protruding portions protruding toward an inside of the circumferential groove from a groove wall reference surface defined as a circumferential surface at a widest groove width position of the circumferential groove and having a first groove wall width surface 12 extending in a tyre width direction and a second groove wall surface having an angle larger than the first groove wall width surface.

A groove bottom is formed symmetrically about a center line of a circumferential groove in a tread plan view and includes groove bottom protruding portions protruding radially outwardly from a groove bottom reference surface parallel to a tread surface at a deepest position of a groove depth. Groove bottom protruding portions have a first groove bottom surface extending radially and a second groove bottom surface having an angle larger than the first groove bottom surface. Groove walls include groove wall protruding portions protruding toward an inner side of the circumferential groove from a groove wall reference surface as a circumferential surface at a widest position of a groove width. The groove wall protruding portions each has a first groove wall width surface and a second groove wall surface having an angle larger than the first groove wall width surface.

In a pneumatic tire including a plurality of main grooves extending in a tire circumference direction and ribs interposed between the two main grooves out of the plurality of main grooves, the ribs include a narrow groove including first narrow groove portions extending in one direction and second narrow groove portions extending in a direction different from the one direction and being arranged alternately in a zigzag pattern, the first narrow groove portions each include a bent portion and a narrow groove bottom sipe at a groove bottom of a portion including the bent portion.

A molding element having a molding surface forming a contact face and a groove forming rib portion forming the groove comprising two opposed rib side faces and a rib top face connecting two rib side faces, the groove forming rib portion provides at least one space opening to at least one of the rib side faces and/or to the rib top face. An insert is received in the space. The insert comprises a cavity for forming a closing device in the groove. The cavity has two opposed cavity faces and opens to at least two faces of the insert corresponding to the faces of the groove forming rib portion. The insert comprises at least one cutting means extending and/or projecting in a direction the groove forming rib portion extends for cutting a material filled in the cavity during demolding.

A tire comprises a tread portion provided with at least one longitudinal groove extending in a tire circumferential direction. The longitudinal groove has a groove bottom surface and a pair of groove wall surfaces extending outwardly in a tire radial direction from the groove bottom surface. The groove bottom surface is provided with a groove bottom protruding portion protruding outwardly in the tire radial direction. At least one of the pair of the groove wall surfaces is provided with a groove wall protruding portion protruding toward a side of a groove center of the longitudinal groove.

The tread has a contact face intended to come into contact with ground during rolling and comprising at least one primary groove having depth D and being delimited by groove sidewalls. The groove sidewalls are axially connected by a groove bottom. The primary groove is provided with a closing device including at least two flexible fences. A first flexible fence has a thickness t1 extending from the groove bottom, and a second flexible fence has a thickness t2 extending from one of groove sidewalls toward the other. The flexible fences are distant each other in an orientation the primary groove extends with a gap g and overlap partly in sectional view of the primary groove. The gap g is at most equal to 1.0 mm. This tread provides further satisfactory reduction on groove resonance and productivity for manufacturing such tread.

A tread for a tire includes a first circumferential groove extending in a circumferential direction entirely encircling the tire, the first circumferential groove having two sidewalls extending radially outward from an annular base, each sidewall defining a plane perpendicular to a rotational axis of the tire, and a first groove rib projecting radially outward from the annular base of the first circumferential groove, the first groove rib extending circumferentially and entirely encircling the tire, the first groove rib having two sidewalls extending radially outward from the annular base of the first circumferential groove to a radially outermost annular surface of the first groove rib, each sidewall of the first groove rib defining a plane perpendicular to a rotational axis of the tire, the sidewalls of the first circumferential groove extending circumferentially and parallel to the sidewalls of the first groove rib, the first groove rib having a radial height less than a radial height of the first circumferential groove.

A pneumatic tire has a main groove (3) provided to a tread part (2). A groove bottom (12) includes a protrusion portion (13) that is convex outward in a tire radial direction. The protrusion portion (13) continues along the main groove (3). The width (W3) of the protrusion portion (13) in a direction perpendicular to a groove center line (G1) of the main groove (3) is 50% to 100% of the groove width (W1) of the main groove (3). The protrusion portion (13) juts outward in the tire radial direction from an imaginary groove bottom (12A) that connects an inner end (10i) of a first groove wall (10) and an inner end (11i) of a second groove wall (11) in a straight line, and the cross-sectional area of the protrusion portion (13) is 3% to 15% of the transverse cross-sectional area of the main groove (3).

Provided is a pneumatic tire where a main groove extending in a tire circumferential direction and a projection projecting toward the inside of the main groove from a groove side wall of the main groove are formed on a tread portion, wherein a projecting amount of the projection from the groove side wall is decreased as the projection extends to a groove bottom of the main groove, the projection terminates at a position outside the groove bottom in a tire radial direction, and a length of the projection along the tire circumferential direction is shortened as the projection extends to a distal end side of the projection in a projecting direction.

A heavy duty pneumatic tire includes a tread portion provided with a zigzag central main groove having zigzag pitches of from 40 to 50. The central main groove includes a bottom and a pair of groove walls. Each groove wall includes a bottom side steep sloped portion and a top side gentle sloped portion. The steep sloped portion includes a height of from 10% to 35% of a depth of the central main groove and an angle of from 0 to 10 degrees with respect to a tire normal line of a tread ground-contact surface. The gentle sloped portion extends radially outwardly from the steep sloped portion. Each groove wall includes an internal corner protruding and an external corner, and the angle of the gentle sloped portion decreases in a range of from 15 to 25 degrees from the internal corner toward the external corner.