Tire (1) for a heavy-duty vehicle of civil engineering type, and more particularly to the tread (2) thereof, and seeks to improve the grip thereof, while at the same time ensuring a satisfactory compromise with wearing and thermal endurance. The tread (2) comprises cuts (3, 4, 5) distributed, in a circumferential direction (XX′) of the tire, among circumferential grooves (3) and, in an axial direction (YY′) of the tire, transverse sipes (4) and transverse grooves (5), the cuts (3, 4, 5) delimiting elements in relief (6), each cut (3, 4, 5) being delimited by two faces facing one another and each face intersecting the tread surface (21) along an edge corner (311, 321; 411, 421; 511, 521). The tread (2) having a longitudinal edge corners ratio TA.sub.X equal to the ratio L.sub.X/S between the sum L.sub.X of the projections, on to the circumferential direction (XX′), of the effective edge corner lengths, contained in an elementary tread surface portion of surface area S, and the surface area S, and a transverse edge corners ratio TA.sub.Y equal to the ratio L.sub.Y/S between the sum L.sub.Y of the projections, onto the axial direction (YY′), of the effective edge corner lengths, contained in an elementary tread surface portion of surface area S, and the surface area S, the longitudinal edge corners ratio TA.sub.X is at least equal to 4 m.sup.−1 and the transverse edge corners ratio TA.sub.Y is at least equal to 6 m.sup.−1.

A pneumatic tire includes a pair of circumferential main grooves, a plurality of center lug grooves, and center blocks. The pair of circumferential main grooves are disposed on both sides of a tire equatorial plane in a tire lateral direction. The tire equatorial plane is interposed between the pair of circumferential main grooves. The pair of circumferential main grooves extend in a tire circumferential direction and oscillate in the tire lateral direction. The plurality of center lug grooves have both ends connected to the pair of circumferential main grooves. The center blocks are defined by the center lug grooves and the pair of circumferential main grooves. The center lug grooves have bent portions at two or more positions. The center blocks include center narrow grooves having both ends connected to the pair of circumferential main grooves. The center narrow groove has bent portions at two or more positions.

A ground contact region of the tread portion of a studdable tire includes a center region located over a range corresponding to a length of 5 to 25% of a ground contact width from a tire centerline on each of both sides of the tire centerline in a tire width direction; and two shoulder regions located on both sides of the center region in the tire width direction. In each of the center region and the shoulder regions, a plurality of the stud pin installation holes are disposed along each of four or more pin arrangement lines extending in a tire circumferential direction. An average value of adjacent intervals between the pin arrangement lines in the center region is larger than an average value of adjacent intervals between the pin arrangement lines in each of the shoulder regions.

A tyre includes a tread portion including a shoulder land portion which has a tread edge and an axial outer surface extending radially inwardly from the tread edge. The shoulder land portion is provided with shoulder lateral grooves extending inwardly in the tyre axial direction from the tread edge to define shoulder blocks therebetween, and protrusions protruding outwardly in the tyre axial direction from the outer surface. The protrusion includes first protrusions each provided on the respective shoulder blocks and extending in the tyre radial direction, and second protrusions connecting radially inner ends of adjacent two first protrusions such that first bent portions are formed between the second protrusions and the first protrusions. The first protrusions have widths smaller than maximum length in the tyre circumferential direction of the respective shoulder blocks, and the second protrusions have widths smaller than the width of the first protrusions.

Present invention provides a tread for a tire being provided with a plurality of grooves extending in an orientation having a non-zero angle A with circumferential orientation, at least two circumferentially adjacent grooves delimiting a contact element, the contact element having at least one incision extending in an orientation substantially parallel to the grooves, the contact element being delimited into sub-contact elements, on a plane perpendicular to the orientation in which the plurality of grooves being extending and to the contact face, each sub-contact elements having a length Ls between the plurality of grooves and the at least one incision or between two incisions, an outermost portion of each the sub-contact element having a radius Rs smaller than a radius Rt of an outline OL of the tread at an intersection between the outline OL and the outermost portion, the radius Rs of the outermost portion of the sub-contact elements is smaller than or equal to 16.0 mm and greater than or equal to 5.0 mm.

A pneumatic tire can suppress uneven wear of the tire and can improve traction performance on snow. Land portions (12A, 12B, 12C), between a pair of outermost side circumferential grooves (11d, 11d) on the outermost sides in the tire widthwise direction among a plurality of circumferential grooves (11a, 11b, 11c, 11d) extending in the tire circumferential direction, are divided into a plurality of blocks (14A, 14B, 14C) by widthwise grooves (13a, 13b, 13c). A pair of groove side faces (13ap, 13aq; 13bp, 13bq; 13cp, 13cq) opposed to each other in the widthwise grooves (13a, 13b, 13c) are bent at bent portions (Kp, Kq) thereof.

The tire includes a tread section (10) including a pair of circumferential main grooves (20), and the tread section (10) includes a center land region (CR) partitioned by the pair of circumferential main grooves (20) and a shoulder land region (SR) partitioned by one circumferential main groove (20) and a tread end (TE). The center land region (CR) forms a dense structure, in which no main groove extending along the tire circumferential direction (TC) is formed. The shoulder land region (SR) includes a block (40) partitioned by a plurality of shoulder lateral grooves (30) crossing in the tire width direction (TW). A sipe (50) extending in the tire width direction (TW) and having one end communicating with the one circumferential main groove (20) is formed in the block (40). A projection (43) projecting inward in the tire width direction is formed on a first groove wall (21) of the circumferential main groove (20) in a corner part (41) of the block (40) formed by intersection of the one circumferential main groove (20) and the shoulder lateral groove (30).

A pneumatic tire includes circumferential main grooves extending in the tire circumferential direction on the tread surface, and in widthwise outermost land portions, widthwise grooves extending from the tread edges inward in the tire width direction and widthwise sipes extending from the tire widthwise inner edge of the widthwise grooves inward in the tire width direction and connecting to the circumferential main groove. Each widthwise sipe includes a widened portion, by the sipe bottom, with a larger sipe width than at the tread surface. A rectangle ratio is 0.8 or more. Each widthwise sipe extends at a first angle relative to the tire width direction in plan view of the tread surface. In a tire radial region containing the widened portion, the widened portion extends at a second angle smaller than the first angle relative to the tire width direction, or partially extends along the tire width direction.

A pneumatic tire includes circumferential main grooves extending in the tire circumferential direction on the tread surface, and in widthwise outermost land portions, widthwise grooves extending from the tread edges inward in the tire width direction and widthwise sipes extending from the tire widthwise inner edge of the widthwise grooves inward in the tire width direction and connecting to the circumferential main groove. Each widthwise sipe includes a widened portion, by the sipe bottom, with a larger sipe width than at the tread surface. A rectangle ratio is less than 0.8. In a tire radial region containing the widened portion, the widened portion includes a portion extending at a first angle relative to the tire width direction. In plan view of the tread surface, each widthwise sipe extends along the tire width direction or at a second angle smaller than the first angle relative to the tire width direction.

A tire tread includes a pair of first circumferential main grooves in a first half-tread region on one side in a tire width direction, a pair of second circumferential main grooves in a second half-tread region, first sipes provided in a first region between the first circumferential main grooves, a circumferential narrow groove having a groove width smaller than a groove width of the first circumferential main groove and extending in the tire circumferential direction within the first region, and sipes in a second region between the second circumferential main grooves, extending in the tire width direction, and closing within the second region. The number of intervals of the second sipes mutually adjacent is larger than the number of intervals of the first sipes mutually adjacent.