A stud pin includes a tip and a body portion provided around a center axis of the stud pin. The body portion includes an upper flange, a lower flange, and a shank portion connecting the upper flange and the lower flange. A first side surface of the lower flange includes a first curved surface recessed inward in relation to the body portion. A second side surface of the upper flange includes a second curved surface bulging toward a periphery of the body portion, and a pair of flat surfaces configured to connect the second curved surface to interpose the second curved surface. A trough portion where the first curved surface is most recessed and a peak portion where the second curved surface is most bulged are located at an identical orientation position about the center axis as viewed from the axial direction.

A stud is for improving grip of a tyre. The stud includes a body having a base flange and a second part, the second part being joined to the base flange, and a pin protruding from the second part in the longitudinal direction (Sz) of the stud. The pin is made of hard metal or ceramic. The base flange has a first cross-section having a first area. The pin has a second cross-section having a second area. A ratio of the first area to the second area is 6.5 to 21. Moreover, the pin protrudes a first height from the second part such that a ratio of the first area to the first height is 20 to 50 mm.sup.2/mm.

A tyre includes a tread having tread blocks; a plurality of stud holes; and a plurality of studs installed in at least some of the stud holes. A constellation of the studs is such that less than two studs are in a line perpendicular to a rolling direction of the tyre. Less than two studs within an area of a footprint are in the same line parallel to the rolling direction. A distance between two adjacent studs is more than 20 mm.

A tyre (200) includes a tread (210) having tread blocks (220) with grooves (230) arranged between the tread blocks (220) and studs (100, 100a, 100b) installed into at least some of the tread blocks (220). A central region (CR) of the tread (210) is arranged between a first shoulder region (SR1) of the tread (210) and a second shoulder region (SR2) of the tread (210). At least some of the tread blocks (220) are provided with sipes (240). The tyre (200) has a first density of sipes (240) in the central region (CR), a second density of sipes (240) in the first shoulder region (SR1), and a third density of sipes (240) in the second shoulder region (SR2). The first density of sipes (240) is at least 15% greater than either or both of the second density of sipes (240) and the third density of sipes (240).

A tyre includes a tread having tread blocks such that grooves are arranged between the tread blocks and studs installed into at least some of the tread blocks. A central region of the tread is arranged between a first shoulder region of the tread and a second shoulder region of the tread. A land ratio of the central region of the tread of the tyre is 1 to 30 percentage points greater than either or both of a land ratio of the first shoulder region of the tread of the tyre and a land ratio of the second shoulder region of the tread of the tyre.

The present invention provides a stud and tool to remove the same.

A tire mold comprises sector molds for forming a tread portion of a tire and mold pins provided on the sector molds for forming insertion holes in the tread portion. The insertion holes each comprise a first hole portion with a first inner diameter where a body portion of a stud pin is disposed and a second hole portion with a second inner diameter greater than the first inner diameter where a bottom flange portion of the stud pin is disposed. The mold pins each comprise a trunk portion with a first outer diameter for forming the first hole portion and a tip portion with a second outer diameter greater than the first outer diameter for forming the second hole portion.

A stud pin (30) arranged in a hole (24) in a tread portion of the pneumatic tire (1), includes: a first flange portion (31) having a first surface that faces the bottom surface of the hole and a second surface that faces in the opposite direction to the first surface; a body (34) connected to the second surface of the first flange portion, and that is arranged in the hole; a tip (35) supported by the body, and that projects to the outer side from the ground contact surface of the tread portion; and a through hole (40) that connects a first opening provided in the first surface and a second opening.

According to a first aspect of the present disclosure, there is provided a stud (100) for a pneumatic tyre. The stud includes a sleeve (120), which comprises or is formed of a thermoplastic elastomer or silicone based material and which comprises a pin hole (126). The stud also includes a pin (110) being formed as a unitary piece form a wear resistant material or compound and inserted into the pin hole (126).

A studded tire includes stud pins embedded in a road contact surface of a tread portion 1; the rubber composition forming the tread portion containing at least one of natural rubber, styrene-butadiene rubber, and butadiene rubber, from 5 to 50 parts by weight of carbon black and from 5 to 70 parts by weight of silica per 100 parts by weight of the diene rubber; a nitrogen adsorption specific surface area of the carbon black being from 50 to 120 m.sup.2/g; a CTAB specific surface area of the silica being from 80 to 190 m.sup.2/g; a rubber hardness of the rubber composition being not greater than 60; and a product of a stress at the time of 400% elongation and a bottom surface area of a flange portion on a bottom side of the stud pins being not less than 400 MPa.Math.mm.sup.2 and not greater than 850 MPa.Math.mm.sup.2.