Pry the plastic center cap of the castle nut mounted to the center bolt with a flathead screwdriver and then place the center cap off to the side.
Bend the ends of the cotter pin straight. The cotter pin goes through the hole in the castle nut. Pull the cotter pin out of the castle nut with a pair of pliers.
Loosen the castle nut with a socket and ratchet. Do not remove the nut at this time.
Lift the corner of the Bolens lawn tractor up and place a jack stand under the rear axle or front suspension to hold the mower off the ground. If the mower is too heavy for you to lift one corner, jack the corner up with a hydraulic jack.
Remove the castle nut from the center bolt and then pull the tire off the Bolens mower.