A wheeled vehicle has a front suspension unit coupled with a body frame to suspend a front wheel. The front suspension unit allows the front wheel to move relative to the body frame. The front suspension unit has a pair of front suspension members coupled with each other. A rear suspension unit is coupled with the body frame to suspend a rear wheel. The rear suspension unit allows the rear wheel to move relative to the body frame. A hydraulic system inhibits a position of the body frame from changing relative to the ground. The hydraulic system has a first hydraulic device to generate hydraulic pressure in response to the movement of the front wheel relative to the body frame. A second hydraulic device generates hydraulic pressure in response to the movement of the rear wheel relative to the body frame. A hydraulic pressure adjusting device connects the first and second hydraulic devices with each other. The hydraulic pressure adjusting device adjusts the hydraulic pressure of the second hydraulic device in response to the hydraulic pressure of the first hydraulic device and vice versa. The first hydraulic device is built in one of the front suspension members.