Patent ID: 7476285
Filing Date: 2009-01-13
Classification: B29D,B60C,D07B,Y10T

Abstract:
1. A method of producing a motorcycle tire, comprising: providing an uncured motorcycle tire comprising a radial carcass ply extending between a pair of bead portions, a belt made of uncured rubberized steel cord members laid on an outer peripheral face of the carcass ply so as to arrange the steel cord members substantially in parallel to an equatorial plane of the motorcycle tire, and a tread rubber and sidewall rubbers laid on outer surfaces of the belt and an uncovered portion of the carcass ply, placing the uncured motorcycle tire in a mold, and subjecting the uncured motorcycle tire to vulcanization under a given internal pressure, characterized in that steel cord members each having either a single twisting construction of 2-7 filaments or a strand bundle construction using such a single twisting construction, and including a space between the mutual filaments over a full length of the cord is used in the belt, and that the belt is enlarged in a radial direction within a range of holding the space between the mutual filaments in the steel cord when the uncured motorcycle tire is pushed onto an inner face of the mold under an inflation of the internal pressure, and that the vulcanization of the uncured motorcycle tire is completed at a state that a coating rubber for the steel cord members in the belt freely fluidizing at a high temperature under a high pressure is penetrated into the full space between the mutual filaments and such a rubber penetration is held by heating the uncured motorcycle tire, wherein the steel cord member used in the belt satisfies a relation of load-elongation curve when the elongation is plotted on an abscissa and the load is a load in an axial direction of the cord that an elongation ranging from a load of zero to a given load indicates a linear gentle gradient and an elongation ranging from a load exceeding the given load to a load corresponding to 70% of a breaking load indicates a linear steep gradient and a connecting line between terminal and start ends of these gradient lines indicates a downwardly convex curve having a small curvature, and a tensile force of a steel cord in a belt of a vulcanized motorcycle tire after assembled onto an nominal rim but before filling with an nominal internal pressure is rendered into a range of loads corresponding to the elongation on the linear gentle gradient in the above relation curve.