Patent ID: 7275573

Claim:
A pneumatic radial ply passenger tire inflated to its nominal pressure, the tire having a tread, a casing with two sidewalls, one or more radial carcass plies extending from and wrapped about two annular beads and a belt reinforcing structure located radially between the tread and the carcass plies, the tread having a first contour-defining curve extending outwards from the equatorial plane of the tire towards the sidewalls, a second contour-defining curve disposed between the first contour defining curve and the sidewalls; and a third contour defining curve disposed between the second contour defining curve and the sidewalls; the first and second contour-defining curves each having respectively first R 1 and second R 2 radiuses such that the length of the first radius R 1 ranges from 400 to 900 mm; and the length of the second radius R 2 is greater than the first radius and ranges from 700 to 1300 mm, the third contour-defining curve having a radius R 3 , wherein the third radius R 3 ranges between 130 and 200 mm, and wherein the second radius (R 2 ) and the third radius (R 3 ) are tangent to each other at a point P 2 , the tangent point P 2 being spaced from the tread edge by a distance of 20 to 40 mm, and wherein there is neither a circumferentially extending groove nor a circumferentially extending elongated void area located within a radius of 10 mm of said point P 2 .