Patent ID: 7387696

Claim:
A method for optimizing and reducing the running noise of a tire provided with a tread having a tread pattern formed of a plurality of tread pattern motifs, this method comprising the following steps: A—forming a first annular distribution from at least two groups of motifs of different respective lengths, this first distribution comprising Ni groups, the ratio between the shortest length and the longest length in the longitudinal direction being equal to Ri; B—creating a second annular distribution from at least two groups of motifs of different respective lengths, this second distribution comprising Nj groups, the ratio between the shortest length and the longest length in the longitudinal direction being equal to Rj; C—calculating a value of an amount of overlap Tij and of the estimated overall pitch ratio R pg from the values Ni, Ri, Nj, Rj using the following formulae wherein M is the total number of distributions: Tij = [ Ni Ri - Nj · Rj ] [ Nj Rj - Ni · Ri ] R pg = Min i = 1 2 ⁡ ( N i ⁢ R i ) Max i = 1 2 ⁡ ( N i R i ) D—comparing the calculated value of Tij with a desired value of between 0.20 and 0.50 and comparing the calculated value of R pg with a desired value of between 0.6 and 0.66; and E—if this calculated value of Tij is not between 0.20 and 0.50 or if the calculated value of R pg is not between 0.60 and 0.66, then modifying at least one value selected from among the values of Ni, Nj, Ri, Rj and resuming steps C and D until the following relationships are satisfied: 0.20 ≦Tij ≦0.50 and 0.60 ≦R pg ≦0.66.