Powered wheeled vehicle (1), capable of travelling both on level ground and over uneven surfaces, comprising at least one driving tread (BR 11) as well as two pairs of front wheels (R61) and rear wheels (R21), of which at least one is a driving pair, wherein each wheel of the driving wheel pair is mounted on a swing arm, each arm of the swing arms (B21) of the rear wheels (R21) is secured to an actuator (V2) for placing said wheels in at least two positions, namely: a first lower position in which the ground-engaging surface of the wheels is below the ground-engaging surface of the tread so that said wheeled vehicle is moved by the wheels alone, and a second position in which the ground-engaging surface of the wheels remains in contact with the ground so that the vehicle is moved by a combination of the tread and said driving wheels.