Tire tread having balanced stiffness

Abstract

A tire includes a first rib having a first circumferential shear stiffness, wherein the first rib has a first plurality of lugs. Each of the first plurality of lugs has a first length. The tire further includes a second rib having a second circumferential shear stiffness substantially equal to the first circumferential shear stiffness. The second rib has a second plurality of lugs, each of the second plurality of lugs having a second length different from the first length. Additionally, the first rib has a different number of lugs from the second rib.

1 . A tire having a circumferential tread, the tire comprising:
 a plurality of circumferential grooves disposed in the circumferential tread, including at least a first circumferential groove and a second circumferential groove;   a plurality of circumferential ribs at least partially defined by the plurality of circumferential grooves, the plurality of circumferential ribs including at least a first circumferential rib, a second circumferential rib, and a third circumferential rib;   a first plurality of lugs formed in the first circumferential rib;   a second plurality of lugs formed in the second circumferential rib, wherein a total number of lugs in the second plurality of lugs is different from a total number of lugs in the first plurality of lugs; and   a third plurality of lugs formed in the third circumferential rib,
 wherein the first circumferential rib has a first circumferential shear stiffness, the second circumferential rib has a second circumferential shear stiffness that is within 5-percent of the first circumferential shear stiffness, and the third circumferential rib has a third circumferential shear stiffness that is within 5-percent of the first circumferential shear stiffness. 
   
     
     
         2 . The tire of  claim 1 , wherein at least a portion of the first plurality of lugs have a first length and at least a portion of the second plurality of lugs have a second length different from the first length. 
     
     
         3 . The tire of  claim 2 , wherein each of the first plurality of lugs has the first length and each of the second plurality of lugs has the second length. 
     
     
         4 . The tire of  claim 1 , wherein at least a portion of the first plurality of lugs have a first geometric shape and at least a portion of the second plurality of lugs have a second geometric shape different from the first geometric shape. 
     
     
         5 . The tire of  claim 4 , wherein each of the first plurality of lugs has the first geometric shape and each of the second plurality of lugs has the second geometric shape. 
     
     
         6 . The tire of  claim 4 , wherein at least a portion of the third plurality of lugs have a third geometric shape different from the first geometric shape and different from the second geometric shape. 
     
     
         7 . The tire of  claim 1 , wherein a total number of lugs in the third plurality of lugs is different from the total number of lugs in the first plurality of lugs. 
     
     
         8 . A tire comprising:
 a circumferential tread;   at least one circumferential groove disposed in the circumferential tread, the at least one circumferential groove at least partially defining a first circumferential rib and a second circumferential rib;   a first plurality of lugs formed in the first circumferential rib, at least a portion of the first plurality of lugs having a first geometric shape;   a second plurality of lugs formed in the second circumferential rib, at least a portion of the second plurality of lugs having a second geometric shape different from the first geometric shape,
 wherein a total number of lugs in the first plurality of lugs is different from a total number of lugs in the second plurality of lugs, and 
 wherein the first circumferential rib has a first circumferential shear stiffness and the second circumferential rib has a second circumferential shear stiffness that is within 5-percent of the first circumferential shear stiffness. 
   
     
     
         9 . The tire of  claim 8 , wherein the second circumferential shear stiffness is within 3-percent of the first circumferential shear stiffness. 
     
     
         10 . The tire of  claim 8 , wherein the second circumferential shear stiffness is within 1-percent of the first circumferential shear stiffness. 
     
     
         11 . The tire of  claim 8 , wherein the at least one circumferential groove includes at least a first circumferential groove and a second circumferential groove, which at least partially define the first circumferential rib, the second circumferential rib, and a third circumferential rib. 
     
     
         12 . The tire of  claim 11 , further comprising a third plurality of lugs formed in the third circumferential rib, at least a portion of the third plurality of lugs having a third geometric shape different from the first geometric shape and different from the second geometric shape. 
     
     
         13 . The tire of  claim 12 , wherein a total number of lugs in the third plurality of lugs is different from the total number of lugs in the first plurality of lugs, and different from the total number of lugs in the second plurality of lugs. 
     
     
         14 . The tire of  claim 13 , wherein the third circumferential rib has a third circumferential shear stiffness that is within 5-percent of the first circumferential shear stiffness and within 5-percent of the second circumferential shear stiffness. 
     
     
         15 . A tire comprising:
 a first rib having a first circumferential shear stiffness, wherein the first rib has a first plurality of lugs, at least a portion of the first plurality of lugs having a first length; and   a second rib having a second circumferential shear stiffness substantially equal to the first circumferential shear stiffness, wherein the second rib has a second plurality of lugs, at least a portion of the second plurality of lugs having a second length different from the first length,   wherein the first rib has a different number of lugs from the second rib.   
     
     
         16 . The tire of  claim 15 , wherein the second circumferential shear stiffness is within 5-percent of the first circumferential shear stiffness. 
     
     
         17 . The tire of  claim 15 , further comprising a third rib having a third circumferential shear stiffness substantially equal to the first circumferential shear stiffness. 
     
     
         18 . The tire of  claim 17 , wherein the third circumferential shear stiffness is within 5-percent of the first circumferential shear stiffness. 
     
     
         19 . The tire of  claim 17 , wherein the third rib has a third plurality of lugs, at least a portion of the third plurality of lugs having a third length different from the first length. 
     
     
         20 . The tire of  claim 19 , wherein the third length is different from the second length.