Patent ID: 8127811

Claim:
A sipe blade for forming a sipe with one end opened and the other end closed in a land portion on a tread surface of a tire, comprising: a front-end portion having a curved convex rounded, arc-like shape that forms the closed end of the sipe; and a connection-end portion that forms the open end of the sipe being connected to a rib that forms a groove portion, wherein the sipe blade has a thickness that varies from the front-end portion to the connection-end portion, the thickness of the front-end portion is larger than the smallest thickness in a portion between the front-end portion and the connection-end portion, and the thickness of the connection-end portion is not more than 3 mm and is the largest thickness in the portion between the front-end portion to the connection-end portion, inclusive, and the ratio of the largest thickness with respect to the smallest thickness is 1.2 to 3.0, and further wherein the thickness of the sipe blade gradually decreases from the widest part of the front-end portion toward the thinnest portion of the sipe blade having the smallest thickness and then smoothly increases toward the connection-end portion, forming a rounded surface having a curved concave arc-like shape at the connection-end portion, and wherein the sipe blade has a thickness that continuously varies from the curved convex shape to the curved concave shape.