GB1483053A - Pneumatic tyres - Google Patents

Abstract

1483053 Pneumatic tyres DUNLOP Ltd 16 Sept 1974 [22 Sept 1973 6 March 1974] 44539/73 and 10005/74 Heading B7C A heavy-duty pneumatic tyre, e.g. for commercial vehicles, comprises a carcass with a single ply 7 of substantially radially extending inextensible cords and a breaker assembly with three superimposed plies 2-4 of inextensible cords, the ratio of the radius of transverse curvature R of the radially outer surface of the tyre tread 1 to the axial width W of the tread lying in the range 2À75 : 1 to 3À5 : 1, and the cords of two of the breaker plies being disposed at equal and opposite cord angles with the cords of the third ply being disposed at a different cord angle to the cords of the other two plies. The cord angle of the two plies may be 10- 25 degrees and that of the third ply 40-70 degrees. The third, higher cord angle, ply may be the radially outermost one, in which case the breaker plies may progressively increase, Fig. 1, or decrease (Fig. 3b, not shown) in width from the outermost to the innermost or may be arranged such that the third ply is the widest one and the middle ply is narrower than the innermost ply (Fig. 3c, not shown). Alternatively (Fig. 3a, not shown), the higher cord angle ply may be the radially innermost ply and narrower than the middle ply which in turn is wider than the outermost ply. A layer of rubber may be interposed between two of the breaker plies in the central region of the breaker assembly. The maximum axial width B of the breaker assembly may be 90-110% of the tread width W. The cords of the carcass and breaker assembly may be of steel.