Abstract: According to the present invention, when a first point (P1) is set on an end edge on an outer end portion (15a) side of a coupling member (15) and a fifth point (P5) is set on an end edge on an inner end portion (15b) side of the coupling member (15), and when a distance (H1) from the fifth point (P5) to the second point (P2) along a reference straight line (RL) passing through the first point (P1) and a tire axis is set to 0.80 times a reference distance (H) from the fifth point (P5) to the first point (P1) along the reference straight line, a distance (H2) from the fifth point (P5) to the third point along the reference straight line is set to 0.65 times the reference distance (H), and a distance (H3) from the fifth point (P5) to the fourth point (P4) along the reference straight line is set to 0.