With all of the miles put on a riding mower every season, it is just a matter of time before a flat tire occurs. Mower tires are susceptible to sharp sticks, nails, tomato cage wires and a host of other remnants from projects, so it does not take much to puncture them. Fortunately, the repair process isn't difficult for a do-it-yourselfer.
Park the riding mower on hard ground. Leave the mower in gear and set the parking brake. Kill the engine and remove the key.
Mix one tsp. of dishwashing detergent with water in a squirt bottle and shake it well. With this solution, it's easy to identify a slow air leak. Jack up the corner of the mower with the flat tire.
Fill the tire with air, using a foot pump or air compressor. Put enough air in the tire to re-create the leak.
Slowly rotate the tire by hand and saturate it with the soapy water. Pay particular attention to the edges of the tire where it meets the wheel's edge. An air leak causes the soapy water to create large bubbles when the solution wets the area.
Remove debris that may be stuck in the tire with a pair of wire cutters. Do not cut the debris in two--lightly grasp the debris with the cutters to get a good bite and pull the material out.
Shake a can of tire sealer and insert it onto the tire's valve stem. While the can is filling the tire, feel the tire with your free hand to determine when it becomes firm. Remove the can.
Insert the tire pressure gauge onto the valve stem. The recommended tire pressure is listed in the operator's manual, as well as the sidewall of the tire.
Fill the tire with tire sealer until you reach the appropriate pressure. Check the remaining tires with the tire pressure gauge to ensure equal pressure.