Two‐dimensional contact pressure distribution of a radial tire, statically compressed to a flat roadway, is analyzed using a rectangular contact patch. The tire structure is modeled by a spring‐bedded ring belt comprised of a laminated‐biased composite strip. The belt is supported by radial springs simulating the sidewall. The spring constant K r was well defined previously by one of the authors. Deformation of the rectangular flat belt is obtained theoretically. The belt is subjected to inflation pressure, reaction forces transmitted from the spring bed of the tread rubber, and shearing force and bending moment along the belt boundaries brought from side‐wall springs and the detached part of the ring belt. In‐plane membrane forces, which are not uniform in the contact area, due to the friction forces acting between the tread surface and the roadway are also applied. The resulting contact pressure distributions in the circumferential direction are shown to be convex along the shoulder, but concave along the crown center line. This distribution agrees well with the experimental results.
Torsional stiffness of its steel‐cord‐reinforced belt structure affects various characteristics of a radial tire, particularly when it is operating at a camber angle other than zero. We analyzed the torsional stiffness of the belt, with consideration of interply shear deformation, by modeling it with a laminated biased composite strip of unidirectional cord‐reinforced rubber (UDCRR) layers. The coupled torsional‐extensional deformation of the belt was shown to vanish at the particular bias angle of 54.7°. It is pointed out that the torsional rigidities of constituent steel cords, which were not considered in the classical lamination theory, could increase the twisting stiffness of the belt structure over that predicted by the conventional lamination theory. A test specimen of low aspect ratio was fixed at both ends under torque loading for the tests. Experimental results of the torsional stiffness together with the coupled torsional‐extensional strain agreed well with the analytical results.