One of the most important skills that we must learn in life is to change a flat tire. When riding a bike, it is also important to carry all the tools at all times.
When removing the wheel from the bike, use a bike wrench to loosen the nuts or the quick release mechanism. Loosen the brakes to get the front wheel off. For the rear wheel, the wheel must be clear of the chain.
Remove the tire from the rim by wedging the tire lever underneath the tire and pry the lever upward to lift the tire away from the rim. Keep the lever in place and slide another lever underneath the tire and work your way around the rim until one edge of the tire comes free of the rim. Locate the metal valve that is used to inflate the tube. Push the valve stem up until it no longer protrudes through the rim. Hold the valve stem and the tube and pull it out of the tire.
Insert the valve stem of the new tube into the hole of the rim. Insert the edge of the tire onto the rim. Use your fingers to slide the tube between the rim and the tire as you work around the rim. Use the tire levers to put the last part of the tire onto the rim.
Once the entire edge of the tire is inside the rim, use the pump to inflate the tire to the recommended pressure. Put the wheel back on the bicycle by reattaching the nuts or quick release mechanism. Reset the brakes and replace the chain. Check if the wheel is properly aligned by spinning the wheel hard and allowing it to turn freely. Lastly, when the wheel spins cleanly, give it a test ride.
Fiedler, D. (2007). How to Change a Flat Tire. Retrieved January 18, 2008 from http://bicycling.about.com/od/bikemaintenance/ss/flat_fix.htm