Abstract: A land ratio of a shoulder portion Sh of a tread portion is 57 to 72%, and a land ratio of a center portion Ce is 40 to 55%. In the center portion Ce, one row block made up of center blocks is formed. Each of the center blocks has its width gradually reduced from a position establishing an axial maximum width BW toward both a leading end and a trailing end relative to the tire rotating direction, each of the center blocks being provided with, at the leading end thereof, a tip portion that sharpens toward the leading end, and being provided with, at the trailing end thereof, a concave portion that smoothly concaves toward the leading end. In each of the center blocks, a ratio (BL/BW) between the axial maximum width BW and a maximum length BL in the circumferential direction is 1.00 to 1.20.

Abstract: A land ratio of a shoulder portion Sh of a tread portion is 57 to 72%, and a land ratio of a center portion Ce is 40 to 55%. In the center portion Ce, one row block made up of center blocks is formed. Each of the center blocks has its width gradually reduced from a position establishing an axial maximum width BW toward both a leading end and a trailing end relative to the tire rotating direction, each of the center blocks being provided with, at the leading end thereof, a tip portion that sharpens toward the leading end, and being provided with, at the trailing end thereof, a concave portion that smoothly concaves toward the leading end. In each of the center blocks, a ratio (BL/BW) between the axial maximum width BW and a maximum length BL in the circumferential direction is 1.00 to 1.20.

Abstract: To improve the steering stability on a wet road surface. A land ratio of a shoulder portion Sh of a tread portion 2 is 57 to 72%, and a land ratio of a center portion Ce is 40 to 55%. In the center portion Ce, one row block made up of center blocks 6 is formed. Each of the center blocks 6 has its width gradually reduced from a position establishing an axial maximum width BW toward both a leading end and a trailing end relative to the tire rotating direction, each of the center blocks being provided with, at the leading end thereof, a tip portion 6a that sharpens toward the leading end, and being provided with, at the trailing end thereof, a concave portion 6b that smoothly concaves toward the leading end. In each of the center blocks 6, a ratio (BL/BW) between the axial maximum width BW and a maximum length BL in the circumferential direction is 1.00 to 1.20.

Abstract: A pneumatic tire comprises a tread portion provided with a plurality of v-shaped main oblique grooves extending from one of tread edges to the other, and a plurality of connecting grooves each disposed on one side of the tire equator to connect between the circumferentially adjacent main oblique grooves at a position near the tire equator, whereby the tread portion is divided into a plurality of center blocks arranged on the tire equator, and a plurality of shoulder blocks disposed on each side of the tire equator and each extending from one of the connecting grooves to the tread edge passing between the circumferentially adjacent main oblique grooves. The axially innermost ends of the shoulder blocks are positioned axially inside the axially outermost ends of the center blocks, and the circumferential dimension L2b across the shoulder block is gradually increased towards the tread edge.

Abstract: A land ratio of a shoulder portion Sh of a tread portion 2 is 57 to 72%, and a land ratio of a center portion Ce is 40 to 55%. In the center portion Ce, one row block made up of center blocks 6 is formed. Each of the center blocks 6 has its width gradually reduced from a position establishing an axial maximum width BW toward both a leading end and a trailing end relative to the tire rotating direction, each of the center blocks being provided with, at the leading end thereof, a tip portion 6a that sharpens toward the leading end, and being provided with, at the trailing end thereof, a concave portion 6b that smoothly concaves toward the leading end. In each of the center blocks 6, a ratio (BL/BW) between the axial maximum width BW and a maximum length BL in the circumferential direction is 1.00 to 1.20.

Abstract: The present invention provides a rubber composition, which has improved gripping performance that is required in a competition tire, high hardness and high stiffness. Specifically, the present invention provides a rubber composition comprising 10 to 100 parts by weight of carbon black having nitrogen-adsorbing specific surface area of 160 to 300 m2/g, and 15 to 70 parts by weight of an oil, based on 100 parts by weight of a rubber component comprising 20 to 95% by weight of a styrene butadiene copolymer rubber having styrene content of at least 30% and vinyl content of at least 30% and 5 to 80% by weight of butadiene rubber, and silica in an amount of 20 to 100% by weight of the carbon black; wherein the total amount of the carbon black and the silica is 20 to 120 parts by weight.

Abstract: The present invention provides a rubber composition, which has improved gripping performance that is required in a competition tire, high hardness and high stiffness. Specifically, the present invention provides a rubber composition comprising 10 to 100 parts by weight of carbon black having nitrogen-adsorbing specific surface area of 160 to 300 m2/g, and 15 to 70 parts by weight of an oil, based on 100 parts by weight of a rubber component comprising 20 to 95% by weight of a styrene butadiene copolymer rubber having styrene content of at least 30% and vinyl content of at least 30% and 5 to 80% by weight of butadiene rubber, and silica in an amount of 20 to 100% by weight of the carbon black; wherein the total amount of the carbon black and the silica is 20 to 120 parts by weight.

Abstract: A bias tire comprises a tread portion, a pair of sidewall portions, a pair of bead portions each with a bead core therein, a carcass extending between the bead portions and comprising two cross plies of cords, and a tread rubber disposed radially outside a crown portion of the carcass to define a tread face, wherein the loss tangent of the tread rubber is in a range of 0.40 to 0.60 under a temperature of 50 deg.C., the distance between the tread rubber and the adjacent cords of the radially outermost carcass ply is at most 1.0 mm, and the two cross plies include at least one ply of PEN cords made of polyethylene 2,6 naphthalate fibers twisted together.

Abstract: A bias tire comprises a tread portion, a pair of sidewall portions, a pair of bead portions each with a bead core therein, a carcass extending between the bead portions and comprising two cross plies of cords, and a tread rubber disposed radially outside a crown portion of the carcass to define a tread face, wherein the loss tangent of the tread rubber is in a range of 0.40 to 0.60 under a temperature of 50 deg.C., the distance between the tread rubber and the adjacent cords of the radially outermost carcass ply is at most 1.0 mm, and the two cross plies include at least one ply of PEN cords made of polyethylene 2,6 naphthalate fibers twisted together.