Pneumatic tire with annular sidewall concavity

Abstract

A pneumatic tire has a non-stretchable tread (30) flanked by two shoulder regions (34), and two non-stretchable bead regions (36) for mounting the tire to a wheel, each bead region being connected via a sidewall to the corresponding bead region. Each sidewall has a first portion (38) extending inwardly relative to a width of the tire from one of the bead regions (36) to a deflection region (40), and a second portion (42) extending outwardly relative to the width of the tire from the deflection region (40) to a corresponding one of the shoulder regions (34). A non-stretchable girth-limiting configuration (44, 46, 56) and a radial reinforcing structure (48, 50, 52) are associated with the first portion (38) of each of the sidewalls, thereby limiting radial flexing of first portion (38) and maintaining an annular concavity between the bead region (36) and the shoulder region (34).

What is claimed is: 
     
         1 . A tire comprising:
 (a) a tread encircling a tire axis, said tread extending between two shoulder regions;   (b) two bead regions for mounting the tire to a wheel;   (c) two sidewalls, each of said sidewalls comprising a first portion extending inwardly relative to a width of the tire from one of said bead regions to a deflection region and a second portion extending outwardly relative to the width of the tire from said deflection region to a corresponding one of said shoulder regions; and   (d) a stiffening structure incorporated into said first portion of each of said sidewalls, said stiffening structure comprising a metal spring fixed in a rubber matrix, said metal spring comprising a plurality of substantially straight portions each extending a majority of a distance from said bead to said deflection region, each of said substantially straight portions being interconnected at each end via a smoothly-curved connecting portion to adjacent of said substantially straight portions.   
     
     
         2 . The tire of  claim 1 , wherein each of said substantially straight portions lies in a radial plane parallel to the tire axis. 
     
     
         3 . The tire of  claim 1 , wherein each adjacent pair of said substantially straight portions lie in an oblique plane that is obliquely angled to the tire axis, and wherein said smoothly-curved connecting portion interconnecting said adjacent pair of said substantially straight portions is curved so as to lie partially outside said oblique plane. 
     
     
         4 . The tire of  claim 3 , wherein said smoothly-curved connecting portions nearer to said bead are curved out of said oblique plane towards the tire axis, and wherein said smoothly-curved connecting portions nearer to said deflection region are curved out of said oblique plane away from the tire axis. 
     
     
         5 . The tire of  claim 1 , wherein said substantially straight portions and said smoothly-curved connecting portions are integrally formed from steel wire. 
     
     
         6 . The tire of  claim 1 , wherein said metal spring is bonded with said rubber matrix. 
     
     
         7 . The tire of  claim 1 , wherein the tire is a pneumatic tire.