PNEUMATIC TIRE

摘要

[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 R1 of 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.

主权项

1. A method for determining a carcass profile of a tire that includes a carcass, a belt layered over the carcass, and beads, the method comprising the steps of:
forming a representative carcass profile for a tire having a representative tire width, among tires for one aspect ratio, by applying a natural equilibrium shape theory, the representative carcass profile being a carcass profile having a natural equilibrium shape; and calculating a carcass profile based on the natural equilibrium shape theory, by using positions of four specific points of a point A, a point B, a point C, and a point D of a tire which has the same aspect ratio as the tire having the representative tire width and which has another tire width, the point A, the point B, the point C, and the point D corresponding to four specific points on the carcass profile, having the natural equilibrium shape, of the tire having the representative tire width, wherein in the carcass profile calculating step, the following mathematical expression for calculating a tire internal pressure share ratio Tb of the belt at any of positions Z on the carcass in a range in which the carcass and the belt are layered, is used
Tb=τo−a(ZA−Z)/(ZA−ZB), ZA corresponds to a coordinate position of the point A in a Z-axis direction, ZB corresponds to a coordinate position of the point B in the Z-axis direction, on a cross-section perpendicular to a circumferential direction of the tire, the point A is a point of intersection of the carcass and a tire equator plane in a coordinate system in which: an originating point is a point of intersection of the tire equator plane and a tire rotation axis; a Y-axis represents a tire rotation axis direction; and a Z-axis represents a tire radial direction, the point B is a separation start point, in the coordinate system, at which the carcass and the belt separate from each other, τo represents a tire internal pressure share ratio of the belt at the point A, a represents a reduced amount of the share ratio τo at the point B, and a range from which values of τo and a are each selected, is provided for each aspect ratio of the tire.