Abstract: A brake system having inlet valves in brake lines between the master brake cylinder and the wheel brakes of the rear axle. The inlet valves are driven via a first current circuit by an electronic analyzing and controlling unit, so that both an ideal brake force distribution is achieved and locking of the wheels is prevented. In order to avoid excessive braking of the rear wheels upon malfunction of the control unit, a second current circuit is provided which comprises a pressure switch responding to the master cylinder pressure. The two current circuits are actuated optionally by way of a relay.