An air suspension system for a non-drive steering axle includes a set of air springs supported on an axle beam extending between a pair of rotating wheels. The axle beam defines a lateral axis about which the wheels rotate. A lateral stiffener assembly cooperates with the axle beam, which provides torsional stiffness, to provide high lateral stiffness in the air suspension system. The lateral stiffener assembly includes a first arm that extends from the axle beam transverse to the lateral axis and is positioned on one lateral side of the vehicle. A second arm extends from the axle beam transverse to the lateral axis and is positioned on an opposite lateral side of the vehicle. Each of the first and second arms has one arm end supported by the axle beam and an opposite arm end mounted to a vehicle frame member.