A pneumatic tire includes a bead portions and a bead core at the bead portions, the tire being mounted to a 15°-tapered specified rim. The bead portions include a portion inward in a radial direction of an extension line of an inner circumferential surface of the bead core, the extension line extending in the lateral direction, that is positioned outward in the tire lateral direction of an imaginary line passing through a first intersection point between the extension line and a tire inner surface and extends inward in the tire radial direction from the extension line at an angle perpendicular to the extension line. An angle α formed by the imaginary line and a line segment passing through a second intersection point between a bead base and the tire inner surface and the first intersection point between the extension line and the tire inner surface is from 0° to 25°.

A pneumatic tire includes a bead portions and a bead core at the bead portions, the tire being mounted to a 15°-tapered specified rim. The bead portions include a portion inward in a radial direction of an extension line of an inner circumferential surface of the bead core, the extension line extending in the lateral direction, that is positioned outward in the tire lateral direction of an imaginary line passing through a first intersection point between the extension line and a tire inner surface and extends inward in the tire radial direction from the extension line at an angle perpendicular to the extension line. An angle α formed by the imaginary line and a line segment passing through a second intersection point between a bead base and the tire inner surface and the first intersection point between the extension line and the tire inner surface is from 0° to 25°.

In this pneumatic tire, the bead core has a predetermined wire array structure obtained by arranging wire cross-sections of bead wires in a cross-sectional view in a tire meridian direction. The following are defined in the wire array structure: a tangent line that contacts, from the side of a rim fitting face, an innermost layer in the tire radial direction and the wire cross-section on the innermost side and the outermost side in the tire lateral direction; contact points of the tangent line with respect to the wire cross-sections on the innermost side and the outermost side; a middle point of the contact points; and gauges in the tire radial direction from the contact points and middle point to the rim fitting face. In this case, the change rates of the gauges before and after rim assembly each are in the range of 10% to 60%.

A pneumatic tire includes a pair of bead portions each having a respective bead core therein, a carcass extending between the bead portions and including a carcass ply that includes a main portion extending between the bead cores and a pair of turn-up portions turned up around the bead cores, and a pair of bead reinforcing layers being disposed outward in the tire axial direction of the turn-up portions so as to cover outermost ends in a tire radial direction of the turn-up portions. An outer surface of at least one of the bead portions is provided with a recess row including a plurality of recesses spaced in a tire circumferential direction, and in the at least one of the bead portions, an outermost end of the bead reinforcing layer is located outwardly in the tire radial direction of outermost ends of the plurality of recesses.

In a tire 2, chafers 8 each extend from a position axially outward of a corresponding one of beads 10 to a position radially inward of the corresponding one of the beads 10. Sidewalls 6 extend to positions between the beads 10 and the chafers 8, respectively. The chafers 8 extend to positions outward of ends 38 of turned-up portions 44 of a carcass ply 40 in the radial direction. When a side surface 50 represents a portion, of an outer surface of each chafer 8, which contacts with a flange of a rim, an outline of the side surface 50 has an arc C that extends from a heel of the bead 10 portion and projects inward.

In a tire 2, chafers 8 each extend from a position axially outward of a corresponding one of beads 10 to a position radially inward of the corresponding one of the beads 10. Sidewalls 6 extend to positions between the beads 10 and the chafers 8, respectively. The chafers 8 extend to positions outward of ends 38 of turned-up portions 44 of a carcass ply 40 in the radial direction. When a side surface 50 represents a portion, of an outer surface of each chafer 8, which contacts with a flange of a rim, an outline of the side surface 50 has an arc C that extends from a heel of the bead 10 portion and projects inward.

A pneumatic tire is provided. In a meridian cross-section, an external contour shape of the bead core is a polygon formed by common tangent lines of a plurality of circumferential portions of a bead wire, the external contour shape includes a single vertex located toward the outside in a tire radial direction, an internal angle formed by two sides sandwiching the vertex is an acute angle, a bottom side of the external contour shape is inclined with respect to the tire lateral direction by from 2° to 9°, and the carcass layer is bent and folded back along a circumference of the bead core in a bead portion, a folded back portion of the carcass layer from a position of an outer end of the bead core in the tire radial direction extends toward a sidewall portion in contact with a body portion.

In a cross-section of a pneumatic tire, a contour of the bead core is a polygon formed by tangent lines of circumferential portions of a bead wire, the contour includes a vertex with an acute angle and a bottom side opposite the vertex, the carcass layer is folded back along a circumference of the bead core in a bead portion, a folded back portion of the carcass layer from an outer end of the bead core extends in the radial direction, and a distance in the radial direction between a center of an arc profile of a tire outer surface and a straight line extending in the lateral direction through the vertex is within 20% of a radius r of the arc, and a distance in the lateral direction between the center of the arc and a straight line extending in the radial direction through the vertex is within 2r±0.4r.

An insert rubber for improving aerodynamics of a tire and an installation method thereof, and provides an insert rubber for improving aerodynamics of a tire and an installation method thereof, in which, by eliminating a space which is located between a bead of a tire and a flange of a rim, airflow is prevented from being introduced between the bead and the flange while a vehicle travels, and the space between the bead and the flange is filled with the insert rubber, thereby preventing turbulence from being generated in the space between the bead and the flange.

An insert rubber for improving aerodynamics of a tire and an installation method thereof, and provides an insert rubber for improving aerodynamics of a tire and an installation method thereof, in which, by eliminating a space which is located between a bead of a tire and a flange of a rim, airflow is prevented from being introduced between the bead and the flange while a vehicle travels, and the space between the bead and the flange is filled with the insert rubber, thereby preventing turbulence from being generated in the space between the bead and the flange.