BMW's Integral Active Steering is a system available on some BMW models that uses a variable steering ratio with passively steered rear wheels, resulting in improved stability and comfort. The rear wheels can turn up to three degrees, depending on factors such as vehicle speed, wheel speed, and steering angle. Under 37 mph the system steers the rear wheels in the opposite direction as the front wheels, significantly reducing the turning circle and making for easier maneuvering during tight situations. Above 37 mph the system turns the rear wheels in the same direction as the front wheels allowing the vehicle to seemingly glide through corners and increasing comfort, especially for rear passengers. The system can also help keep the vehicle stable, especially when braking with each wheel on a different type of surface.