Abstract: A hydraulic wheel system is provided which comprises a disc, a first piston, a wheel, a tire, a dismount button, and a wheel mounting member. The disc is provided with a first cylinder and a second cylinder communicating with each other. The first piston is slidably disposed within the first cylinder. The wheel is coupled to the disc so that a rotational force of the disc is transmitted to the wheel. The dismount button is configured to move the first piston. The wheel mounting member is provided in the disc. A second piston that is slidably disposed within the second cylinder is integrated with the wheel mounting member. The wheel mounting member is elastically supported by an elastic member in a direction opposite to the predetermined direction, and it is configured to be selectively connected to the wheel in response to a movement thereof.