A pneumatic tire includes a carcass extending between bead cores of bead portions through a tread portion. A tire section width Wt (unit: mm) in relation to a bead diameter Db (unit: inch) satisfies the following equations, Wt0.7257(Db).sup.2+42.763Db339.67, and Wt0.7257(Db).sup.2+48.568Db552.33. In a tread thickness distribution curve f(y) represented by equation f(y)=1t(y)/t(0), when y=0.4, the value of f(y) is of from 0.03 to 0.06, and a rate of change of the value of f(y) increases to y=0.4 and decreases thereafter, where t(y) denotes a tread thickness at each tire axial position Py, and y represents a ratio of an axial distance from the tire equatorial plane, to the maximum-width L of the carcass.

A pneumatic tire mountable on a 15 tapered specified rim, the pneumatic tire including a bead portion, bead core, a carcass, a steel cord reinforcing layer, and a bead rubber layer. A distance from a second line segment to a third line segment is from 4 mm to 8 mm, and a ratio R2/R1 is from 0.935 to 0.975, wherein R2 is a tire radius at a bead toe of a bead base portion and R1 is a tire radius at a bead heel.

A pneumatic tire excellent in resistance to uneven wear, and crack resistance of a groove is provided. A position, on an equator plane, of a tread surface 20 of a tire 2 is represented as a point Pc. A position, at a maximum width, of an axially outer side surface 6a of a sidewall 6 is represented as a point Pe. A position that is a mid-point, in the radial direction, between the point Pc and the point Pe, and that is on the axially outer side surface 6a, is represented as a point Pd. When an internal pressure is enhanced from an internal pressure that is 0.05 times a normal internal pressure P to the normal internal pressure P, a value Fs of difference in amount of protrusion between an amount of protrusion Dd (mm) at the point Pd and an amount of protrusion De (mm) at the point Pe is calculated according to mathematical expression (1) in which a nominal width is represented as W (mm). The value Fs of difference in amount of protrusion is greater than 0.4 and less than 0.5.
Fs=((DdDe)/W)100(1)

An intermediate article of manufacture formed as a first stage bead area subassembly for a split ply pneumatic tire carcass is disclosed. The bead area subassembly has an annular bead core; a bead apex; a ply strip; and preferably a sidewall affixed to the ply strip. The subassembly is formed into a disk-shaped bead area monocomponent. The ply strip is wrapped about the bead core and the apex to form a ply turnup and both the ply strip and the ply turnup extend radially outwardly from the bead core. The bead area subassembly when formed into the disk-shaped bead area monocomponent is placed on an annular holder device.

The tire includes a summit surrounded by side portions terminating in beads provided to cooperate with a mounting rim. A carcass reinforcement is surmounted by a summit reinforcement composed of reinforcing plies. When the tire is mounted onto its standard mounting rim and inflated with its nominal pressure, each side portion has an upper side point, a bottom side point, an intermediate side point, an upper side portion, and a bottom side portion. A weight of the bottom side portion on one side portion is at least 15% lighter than a weight of the bottom side portion on another side portion.

A pneumatic tire has a designated vehicle inner/outer side orientation for when mounted on a vehicle, and includes: a reinforcing rubber layer disposed in sidewall portions on sides in a tire lateral direction, the reinforcing rubber layer having a crescent shaped meridian cross-section; wherein a radius of curvature with an arc joining intersections of straight lines and a tire external contour, and a radius of curvature with an arc joining intersections of the straight lines and a carcass layer have a relationship such that, on the vehicle outer side, a radius of curvature of the carcass layer is large with respect to a radius of curvature of the tire external contour, and on the vehicle inner side, a radius of curvature of the carcass layer is small with respect to a radius of curvature of the tire external contour.

[Object] A pneumatic tire 2 that allows achievement of reduction of rolling resistance without taking influence on a mass into consideration, is provided. [Solution] A profile OL of the tire 2 includes a ground-contact surface 46 and a pair of side surfaces 48. In the profile OL, a zone from a point PB to a point PW is formed by three arcs. The arcs are a first arc, a second arc that extends almost outward from the first arc in the radial direction, and a third arc that extends almost outward from the second arc further in the radial direction. A ratio of a radius R2 of curvature of the second arc to a radius R1of curvature of the first arc is greater than or equal to 1.45 and not greater than 3.26. A ratio of a radius R3 of curvature of the third arc to the radius R1 of curvature of the first arc is greater than or equal to 0.45 and not greater than 0.56. Each sidewall 8 of the tire 2 has a first recess 50a and a second recess 50b that are recessed inward from the side surface 48.

A pneumatic tire includes a reinforcing rubber layer disposed in the sidewall portions and having a crescent-like meridian cross-section; wherein when the tire is assembled on a regular rim and in an unloaded state with an internal pressure of 0 kPa, a radius of curvature (RP) is larger than a radius of curvature (RO), an arc of the radius of curvature (RP) joining an intersection (Pa) of a carcass layer and a straight line (La), an intersection (Pb) of the carcass layer and a straight line (Lb), and an intersection (Pc) of the carcass layer and a straight line (Lc), and an arc of the radius of curvature (RO) joining an intersection (Oa) of the straight line (La) and a tire external contour, an intersection (Ob) of the straight line (Lb) and the tire external contour, and an intersection (Oc) of the straight line (Lc) and the tire external contour.

A pneumatic tire includes a reinforcing rubber layer disposed in the sidewall portions, the reinforcing rubber layer having a crescent-like meridian cross-section. When the tire is assembled on a regular rim and in an unloaded state with an internal pressure of 0 kPa, a radius of curvature (RP) is smaller than a radius of curvature (RO), an arc of the radius of curvature (RP) joining an intersection (Pa) of a carcass layer and a straight line (La), an intersection (Pb) of the carcass layer and a straight line (Lb), and an intersection (Pc) of the carcass layer and a straight line (Lc), and an arc of the radius of curvature (RO) joining an intersection (Oa) of the straight line (La) and a tire external contour, an intersection (Ob) of the straight line (Lb) and the tire external contour, and an intersection (Oc) of the straight line (Lc) and the tire external contour.

A tire 1 for motorcycles comprises a carcass 6, a belt layer 7, and a tread rubber 2G. The belt layer 7 includes at least one reinforcing cord coated with rubber and spirally wound. In a meridian section passing through a tire rotational axis of the tire 1 in a standard state, a width BW of the belt layer 7 in a tire axial direction is in a range of from 60% to 80% of a tread width TW. The tread rubber 2G has a thickness at a tire equator (C) in a range of from 70% to 90% of thickness at tread edges (2t).