GB1360203A - Tyre treads - Google Patents

Abstract

1360203 Pneumatic tyres DUNLOP HOLDINGS Ltd 28 June 1971 [3 July 1970] 32304/70 Heading B7C A pneumatic tyre, e.g. for a heavy vehicle, has a tread comprising tortuous, e.g. zig-zag, axial grooves 11 extending for a distance of between “ and ¢ of the total tread width T from each tread edge to define axial bars 18, and a pair of circumferential grooves 17, e.g. of zig-zag form as shown, of lesser depth than the grooves 11 and disposed one one each side of the tyre equator X-X, for each groove 17 the circumferential plane lying midway between the axially innermost and outermost extremities of the groove being located at a distance of between T/10 and T/4 from the nearer tread edge such that the grooves 17 divide the bars 18 and intersect each groove 11 between its ends, both the grooves 11 and 17 being 'wide', i.e. of sufficient width to remain open in the tread/ground contact patch in use. The tread may, as shown, also have axial zig-zag grooves 16 which are 'narrow', i.e. of such width as to close in the tread/ground contact patch in use, and there may be other 'wide' grooves in the tread in addition to those 11, 17. The grooves 17 may have a lesser depth adjacent their intersections with the grooves 11 than at points away from these intersections. Each zig-zag groove 11 may, as shown, have four limbs 12-15 whose respective inclinations to the tyre axis are' 10, 20, 25 and 55 degrees. The tyre may have a cross-ply carcass.