If you have a lawnmower with a pneumatic, or air-filled, tire, you will eventually need to fix a flat tire or change the tire. Many pneumatic tires use inner tubes. The process for repairing a flat on a tire with an inner tube is similar to repairing a tubeless tire. Both tires can be repaired by only removing one side of the tire. In many cases, getting the side of the tire free can be the most difficult part of repairing your flat tire.
Remove the tire from your lawn mower by removing the lug nuts with a lug wrench.
Remove the valve stem with a stem wrench to allow air to flow freely in and out of the tire.
Lay the tire on its side and slip a tire spoon between the tire bead and the rim. The tire bead is the portion of the rubber that meets the rim. If you don't have tire spoons, flat blade screwdrivers can work well. However, be very careful not to further puncture the tire's inner tube when using screwdrivers.
Pry the bead over the rim edge and slip another tire spoon next to the first.
Slide the second tire spoon around the tire to separate one side of the tire from the rim.
Slip the inner tube out of the tire and reinsert the valve stem, if the tire has a tube. Partially inflate the tube and locate the leak by immersing the inner tube in a tub of water. Remove the object that caused the puncture from the tire, whether the tire is tubeless or uses an inner tube. If the tire is tubeless, mark the location on the inside of the tire.
Patch the puncture by following the directions on the patch kit. The precise directions will vary, depending on the kit. If patching an inner tube, patch the tube and reinsert it in the tire. If patching a tubeless tire, patch the hole with the rim still attached to one side of the tire.
Remove all air from the inner tube, if your tire uses one, and insert the tube in the tire.
Work the tire bead back on to the tire with the tire spoons and inflate the tire.