Going to a professional tire-repair service is your safest option of fixing a flat tire. Most flats can be easily plugged at a shop properly, and it is very inexpensive to do so. Tire-plugging is very safe, and lasts as long as your tires last. If you have a hole in the sidewall of your tire, plugging will not be what you need, and more than likely you will need a new tire. It is important to keep the tires consistent to brand and performance, so going to a service can ensure that you get exactly what you need.