Patent ID: 7178569

Claim:
A support ring for a runflat tire system comprising an annular body made of an elastic material having a radially inner circumferential surface which fits to a mounting portion of a wheel rim when mounted thereon, and a radially outer circumferential surface which comes into contact with the inside of the tread portion of a pneumatic tire mounted on the wheel rim when the tire is deflated and loaded, wherein the outer circumferential surface is wider in the axial width than the inner circumferential surface, and in a cross section including the central axis of the support ring, the outline of the annular body is substantially a trapezoidal shape of which two parallel long and short sides are the outer and inner circumferential surfaces, respectively, and the remaining two sides are inclined at acute angles with respect to the long side, and said annular body comprising: a radially outer wide annular portion whose radially outer surface defines said outer circumferential surface; a radially inner narrow annular portion whose radially inner surface defines said inner circumferential surface; and a supporting wall portion between the radially outer and inner annular portions, wherein the supporting wall portion comprises circumferential walls and traverse walls, the circumferential walls extend radially outwardly from the axial edges of the radially inner annular portion to the axial edges of the radially outer annular portion, while inclining axially outwards to define said trapezoidal profile, and the traverse walls each extend from one of the circumferential walls on one side of the annular body to one of the circumferential walls on the other side of the annular body, said supporting wall portion extends continuously in the circumferential direction of the support ring in a zigzag fashion, wherein the circumferential walls on one side of the annular body are staggered with respect to the circumferential walls on the other side of the annular body, each of the circumferential walls extends in parallel with the circumferential direction of the support ring, the transverse walls are alternately inclined in the same direction with respect to the axial direction of the support ring so that each transverse wall has an overall inclining direction, and each of the transverse walls is made up of at least three axial parts and at least two oblique parts therebetween arranged in a zigzag fashion, wherein said at least two oblique parts are inclined to the same direction as the overall inclining direction of the transverse wall.