Sub-tread reinforcement patterns for heavy duty radial ply tyres - involving alternate plies of differing width and offset angle to suppress delamination

摘要

Subtread reinforcement for pneumatic tyres comprises >=3 concentric bandages of differing widths where one metallic cord ply having a cord axis offset by 60-70 degrees from the circumferential axis is laid between two layers with their cord axis offset by 15-25 degrees and of the opposite bias to the ply between them. The central ply may be narrower or wider than the plies each side of it. The combination of a highly offset axis ply with adjacent plies of dissimilar width stiffens the tread zone against deformation of transverse curvature and minimises destructive interaction of peripheral stresses which tend to cause delamination from the matrix rubber. Stiffness gradients across the tyre structure are smoother than for tyres with superimposed reinforcement layers of similar width and degrees of bias.