To plug a flat tire, locate the hole in the tire, remove the object from the tire if necessary, and obtain a plug kit. Use the filing tool provided in the kit to clean the hole, and thread a plug through the eye of the second tool in the plug kit. Insert the tool and plug into the hole in the tire until 1/2 inch of the plug extends out of the tire. Pull the tool off the plug.
Use as much force as necessary to insert the plug, and pull the tool straight up and away from the tire to remove it while leaving the plug in place. If the hole isn't visible, brush soapy water onto the tire, and examine the tire for bubbles. The area where new bubbles appear in the water indicates a hole in the tire.
After placing the plug in the tire, use scissors to remove the excess plug, and air the tire up to the recommended pressure. Do not use a plug to repair the tire if the sidewall is damaged or if the tire is excessively worn. A plug is intended as a temporary repair, and the tire should be replaced as soon as possible to avoid issues.