To provide a wheel with a simple constitution capable of automatically adjusting the air pressure in a tire utilizing rotation action of the wheel during traveling.

A cylinder device 3 is provided in a radial direction of a wheel body 2. The cylinder device 3 includes a cylinder body 4; a piston 5 reciprocable in the cylinder body 4; and a resilient member 6 connected to the piston 5. In the state that centrifugal force is not applied to the piston 5, the resilient member 6 allows the piston 5 to be moved to a position where the volume in the cylinder body 4 is made minimum when the centrifugal force is applied to the piston 5 by rotation action of the wheel body 2, while drawing the piston 5 near a position where a volume in the cylinder body 4 becomes maximum.