PNEUMATIC TIRE

A pneumatic tyre having a toroidal carcass. The tyre satisfies the following expressions (1) to (4): Ra/D≤0.08 Rb/D≤0.08 0< phi a≤50 DEG and 0< phi b≤50 DEG where, in a tyre meridional section in a standard state in which the tyre is mounted on a standard wheel rim, inflated to standard inner pressure, and not loaded, Ra is a radius of curvature of a first arc having a centre Oa on a tyre axial direction line X passing through a midpoint between a first point A and a second point B and on a tyre inner cavity side and in contact with a tyre centre line at the first point A, the first point A being a point where a tyre radial direction line Y passing through a wheel rim width position of the standard wheel rim intersects the tyre centre line passing through a midpoint of a thickness of the tyre on a tread portion side and a second point B being a point where the tyre radial direction line Y intersects the tyre centre line on a bead portion side, Rb is a radius of curvature of a second arc having a centre Ob on the tyre axial direction line X and on the tyre inner cavity side and in contact with the tyre centre line at the second point B, phi a is an angle formed by the tyre axial direction line X and a straight line Oa-A connecting the centre Oa and the first point A, phi b is an angle formed by the tyre axial direction line X and a straight line Ob-B connecting the centre Ob and the second point B, and D is an outer diameter of the tyre.