Find the screws that hold the tractor seat in place. Depending on the manufacturer, the screws either sit along the sides of the seat, on top of the seat or slightly below the seat. Unscrew the seat and place the screws in a safe place, such as your pocket.
Run the knife along the edge of the seat, poking the edge of the knife through the vinyl or fabric covering and into the padding. Strip away everything until you reveal the metal frame. Set the rubber edge of the seat to one side.
Press the upholstery foam against the seat and run your knife around the edges. Create a basic outline of the seat in the foam and throw away the excess foam. Push the foam back against the seat and remove any areas that overhang the seat.
Shake the spray adhesive can lightly in your hands and spray both the foam and the seat with the adhesive. Hold the foam over the seat, making sure that you know where to place it. Drop the foam on the seat and press down gently. It may take up to 20 minutes before the adhesive dries.
Add more adhesive to the top of the foam. Lay the vinyl or fabric on top and run your hands across the top, pressing it into the adhesive and removing air bubbles. Spray more adhesive on the sides of the foam and work the fabric down until it completely covers the foam. Trim off any excess fabric or vinyl. Slip the rubber piece you put aside earlier back on the tractor seat. The piece holds the fabric in place and keeps water from seeping inside.