Safety tyre

Claim 1

A pneumatic tyre having a tread portion (5) ,a pair of bead portions (3) , a pair of sidewall portions (4) therebetween, a pair of bead cores (2) one disposed in each bead portion (3) , a carcass (6) extending between said bead portions (3) through said sidewall portions (4) and the tread portion (5) and turned up in both edges around the bead cores (2) to be secured thereto and to form carcass turnup portions and a main carcass portion therebetween, a belt (19) disposed between the tread (5) and the carcass (6) and having cords laid at a relatively small angle to the tyre equator and a pair of bead apexes (9) one disposed between the carcass main portion and each of the carcass turnup portions characterised in that when the tyre (1) is assembled on its specified rim (14) and inflated to its design specified pressure, the aspect ratio of the tyre which is designed as the tyre sectional height (H) divided by the tyre maximum width (W) is not more than 80%, the axial width (WT) of the tread (5) is greater than the maximum width WC of the carcass (6), each edge (d) of the tread (5) is positioned at a height (hd) within a range of 50 to 100% of the sectional height HC of the carcass (6),the carcass (6) is provided on each side of the tyre equator with a convex arc part (B1) having a radius R1 and a concave arc part (B2) having a radius R2, both radii R1 and R2 being smoothly connected at an inflection point (f) therebetween, the convex arc part (B1) having a centre of curvature (01) positioned inwardly of the tyre and extending radially inwardly from the point (e) of the maximum width WC of the carcass (6) to the inflection point (f) the concave arc part (B2) having a centre of curvature (02) positioned outwardly of the tyre and extending radially inwardly from the inflection point (f) to the arc where the carcass (6) contacts the bead core (2) and the radius R2 of said concave arc part (B2) is greater than the radius R1 of said convex arc part (B1).