The Rheonetic Seat Suspension System consists of (a) a seat damper cylinder that is filled with a magnetic fluid, (b) a sensor that detects vibration and jolting, and (c) an electronic controller that creates a magnetic field to thicken the fluid and dampen the movement of the seat. The fluid can change from a free-flowing liquid to a near-solid instantly, then back to a liquid when the magnetic field is removed. The thicker the fluid, the greater the damping forces provided. This damper can be mounted in place of most tractor seat suspension cylinders.