Patent ID: 8062159

Claim:
A metal ring of a metal belt used in a belt type continuously variable transmission, wherein the metal ring is an innermost ring of a plurality of metal rings which are laminated one on another, and wherein the innermost metal ring comprises: a base material; a free state radius that is set wherein a stress center of an inner peripheral face of the innermost metal ring has a value that does not exceed a compressive elastic deformation limit of the inner peripheral face of the innermost metal ring; and a residual compressive stress due to a thermal treatment; wherein the compressive elastic deformation limit equals the residual compressive stress added to a compressive elastic deformation limit of the base material; wherein the stress center is determined from a variation in stress of the inner peripheral face of the innermost metal ring during operation of the continuously variable transmission as well as a compressive contact stress which occurs when the inner peripheral face of the innermost metal ring contacts a saddle face of a metal element carrying the metal ring therein; and wherein x (MPa) denotes the residual compressive stress of the metal ring due to a thermal treatment, d denotes an inter-shaft distance in millimeters, and Ro denotes the free state radius in millimeters, wherein the following expressions are simultaneously valid: −1300 ≦x <−1000 Ro <4.93 d −557.4, and Ro >0.33 d −4.7.