GB932401A - Improvements in or relating to pneumatic tyres for vehicle wheels - Google Patents

Abstract

932,401. Pneumatic tyre tread. PIRELLI S.p.A. Sept. 17, 1959 [March 18, 1959], No. 31735/59. Class 144 (2). A pneumatic tyre tread A comprises an odd number, such as five, uninterrupted circumferential ribs 1, 5, 6, 11 and 12 separated from each other by uninterrupted zig-zag circumferential channels 2, 3, 7 and 8, each channel being formed from conjoined portions, suffixed a and b, of different lengths with corresponding portions being parallel to each other in each channel, the central rib 1 having parallel 45 degrees knife cuts extending into the rib from the valleys of the channels 2, 3, and knife cuts 9 of the shape shown extending into the ribs 5, 6, 11 and 12 from the channels 2, 3, 7 and 8. The axially outer edges of the outer ribs 11 and 12 are serrated and transverse knife cuts 13 extend therefrom into the ribs 11 and 12. The shoulders B of the tyre are each completed by a series of concentric flattopped circumferential ribs 14. The axially inwardly-facing walls of channels 7 and 8 are formed, on the channel portions 7a and 8a respectively, with integral blocks 10 which project at an inclined angle towards the mid-circumferential plane of the tyre. The blocks are spaced from the base and opposite sidewall of the respective channel and serve to maintain the channel width.