METHOD OF IMPROVING TREAD NOISE
A method of improving tire tread noise is provided. The method allows the identification of locations where the tread pattern should be particularly modified in order to optimize the level of noise created by the tread during tire operation. Variations in a defined parameter, contact length ratio, are used to determine one or more locations in the tread pattern where modification for noise reduction can be made. The type of modifications needed can also be indicated.
1 . A method for improving the noise created by the tread pattern of a tire, the tread pattern having a circumferential direction, the method comprising the steps of
selecting a portion of the tread pattern for evaluation;
determining the variation in contact length ratio along the circumferential direction for the selected portion of the tread pattern; and
reducing the variation in contact length ratio by modifying the tread pattern.
2 . A method for improving the noise created by the tread pattern of a tire as in claim 1 , wherein said determining step further comprises calculating the contact length ratio at each point along the circumferential direction of the selected portion of the tread pattern.
3 . A method for improving the noise created by the tread pattern of a tire as in claim 1 , wherein said determining step further comprises:
mapping the selected portion of the tread pattern; and
calculating the contact length ratio at each point along the circumferential direction of the mapped tread portion of the tread pattern.
4 . A method for improving the noise created by the tread pattern of a tire as in claim 1 , where said reducing step further comprises adding contact surfaces to the tread pattern at one or more points along the circumferential direction of the selected portion based on the variation in contact length ratio provided by said determining step.
5 . A method for improving the noise created by the tread pattern of a tire as in claim 1 , where said reducing step further comprises removing contact surfaces from the tread pattern at one or more points along the circumferential direction of the selected portion based on the variation in contact length ratio provided by said determining step.
6 . A method for improving the noise created by the tread pattern of a tire as in claim 1 , further comprising the step of determining the point along the circumferential direction of the selected portion of the tread pattern at which maximum variation in the contact length ratio occurs.
7 . A method for improving the noise created by the tread pattern of a tire as in claim 1 , further comprising the step of determining the point along the circumferential direction of the selected portion of the tread pattern at which minimum variation in the contact length ratio occurs.
8 . A method for improving the noise created by the tread pattern of a tire as in claim 1 , wherein the portion of the tread pattern from said selecting step is one pitch of the tread pattern.
9 . A method for improving the noise created by the tread pattern of a tire as in claim 1 , further comprising the step of repeating said steps of selecting, determining, and reducing until an acceptable variation in contact length ratio is achieved for the selected portion of the tread pattern.
10 . A method for improving the noise created by the tread pattern of a tire as in claim 1 , where the contact length ratio at given point along the circumferential direction of the tread pattern is defined as:
CLR i =1 −C i /n
where
CLR i =the contact length ratio at a given location i along the circumferential direction
C i =the total number of or points contacting a road surface along a leading edge of the tread pattern at a given location i along the circumferential direction
n=the total number of points along the leading edge
11 . A method for improving the noise created by the tread pattern of a tire as in claim 1 , wherein said determining step further comprises:
mapping the selected portion of the tread pattern;
calculating the contact length ratio at each point along the circumferential direction of the mapped tread portion of the tread pattern; and
plotting the results of said calculating step for each point along the circumferential direction of the mapped tread portion of the tread pattern.
12 . A tire constructed according to the method of claim 1 .
13 . A method of improving tire tread noise, the method comprising the steps of:
determining contact length ratios along a selected portion of the tread;
comparing the contact length ratios to determine locations of maximum and minimum variations in the contact length ratios along a circumferential direction of the tread; and
optimizing the noise to be produced in operation of the tire tread by modifying the maximum and minimum variations in the contact length ratios.
14 . A method of improving tire tread noise as in claim 13 , wherein said optimizing step further comprises the step of modifying the tread pattern so as to change the contact length ratios at the locations of the maximum and minimum variations.
15 . A method of improving tire tread noise as in claim 14 , wherein said optimizing step further comprises adding contact surfaces to the tread pattern at one or more locations along the circumferential direction.
16 . A method of improving tire tread noise as in claim 15 , wherein said optimizing step further comprises reducing contact surfaces of the tread pattern at one or more locations along the circumferential direction.
17 . A method of improving tire tread noise as in claim 16 , wherein the selected portion of the tread is at least one pitch of the tread.
18 . A method of improving tire tread noise as in claim 13 , further comprising the step of repeating said steps of determining, comparing, and optimizing until acceptable variations in contact length ratios are achieved for the selected portion of the tread pattern.