Runflat tire system and support ring therefor

A runflat tire system (1) which comprises a wheel rim (3), a pneumatic tire (2) and a support ring (4) is disclosed. The support ring comprises a radially inner annular portion (6), a radially outer annular portion (5), and a supporting wall (7) extending from the inner annular portion to the outer annular portion, wherein the supporting wall comprises a main wall (8) extending continuously in the circumferential direction in a trapezoidal waveform, and axial walls (9) extending axially outwardly from the main wall.