Tire tread design and the construction method thereof

摘要

A tire tread, comprising a tread pattern formed of groups of motifs arranged, in the transverse direction, in a number M of distributions at least equal to two and of average width Li, Lj, the total of the widths Li, Lj being at least equal to 80% of the width L of the tread, each distribution of groups of motifs being formed by a succession of a plurality of groups, at least two of said groups of motifs of the distribution in question having different longitudinal lengths, the ratio Ri between the longitudinal length of the smallest group of motifs and the largest group of motifs being strictly less than one, this tread being characterized in that for at least two distributions comprising respectively Ni and Nj motifs, with Ni0.20<=T_ij<=0.50, 0.60<=R_pg<=0.66 where Tij, which represents the amount of overlap between the distributions, is calculated by the following formula: $\mathrm{Tij}=\frac{\left[\frac{\mathrm{Ni}}{\mathrm{Ri}}-\mathrm{Nj}.\mathrm{Rj}\right]}{\left[\frac{\mathrm{Nj}}{\mathrm{Rj}}-\mathrm{Ni}.\mathrm{Ri}\right]},$ where R_pg, which designates an "estimated overall pitch ratio" between the M distributions, is obtained by the following formula: $R_{\mathrm{pg}}=\sqrt{\frac{{\mathrm{Min}}_{i=1}^M\left(N_i{R}_i\right)}{{\mathrm{Max}}_{i=1}^M\left(\frac{N_i}{R_i}\right)}}.$