To provide a device for hindering the occurrence of damage as much as possible.

A wheel 1 is formed of a wheel rim 2 and a wheel central member 3 to be connected to a wheel flange 6 of a tractor. A mechanism 8 is provided so as to fill and release the air into/from a tire fitted to the wheel 1. This mechanism is formed of a housing 14 fixed to a wheel central member 3 and to be rotated with the wheel central member. An inner member 21 is supported inside the housing 14. An annular chamber 25 is formed between the two of the housing 14 and the inner member 21. The annular chamber 25 is connected to a first connection port 10 on the wheel rim 2 and connected to a second connection port 11 arranged in a valve 9 through a pipe 12. The annular chamber 25 can be connected to a compressed air generator through a third connection port 29 and a main valve 30.