Abstract: A seat assembly for vehicles such as lawn and garden tractors comprises a base for attachment to the vehicle. The base includes an axle to which a first support plate is pivotally mounted. The first support plate includes a pair of channels. A corresponding pair of runners may be slidably attached to the channels in relative back and forth movement. A second support plate is attached to the runners and is movable therewith. A seat is pivotally attached to a third support plate. An air spring is mounted between the second and third support plates for restricting the movement of the second and third plates toward one another. A pair of struts extend between the second and third support plates for providing relative up and down movement therebetween as the air spring is compressed or expanded during use.