A pneumatic radial ply passenger tire (10) having a tread (20), a casing with two sidewalls (14, 16), one or more radial plies (18) extending from and wrapped about two annular beads (13) and a belt reinforcement structure (15) located radially between the tread and the plies. The tread has a first contour-defining curve extending outwards from the equatorial plane of the tire towards the sidewalls, an adjacent second contour-defining curve disposed between the first contour defining curve and the sidewalls and an adjacent third contour defining curve extending outwards from the second contour defining curve and the sidewalls. The first, second and third contour-defining curves have first (R1) and second (R2) and third (R3) radii chosen such that R2>R1>R3.