A tire valve stem is a small, rubber tube that extends from the rim of the tire. The valve stem has a spring-loaded valve that allows air to enter or exit the tire. All air-filled tires have valve stems. On an automobile, the valve stem should be replaced when you buy new tires. Valve stem components degrade over time and can lead to slow leaks and a loss of air pressure. Replacing a valve stem is fairly easy, once the tire is removed from the rim.
Remove the tire from the vehicle.
Remove the cap from the valve stem, and press the tip of the valve stem removal tool into the valve, to release the air in the tire.
Place the valve stem removal tool over the end of the valve, and turn it, counterclockwise, to remove the valve from the valve stem.
Use a crowbar and a rubber mallet to break the seal around the edge of the tire, where it fits against the rim. Pry the tire away from the rim.
Note how the valve stem is oriented, and remove the valve stem from inside the tire.
Place the new valve stem inside the tire oriented the same direction as the old valve stem. Pull the valve stem through the hole in the tire, until the ring part is seated in the hole. Use lubricant, if needed, to slide the new valve stem through the hole.
Remove the cap from the new valve stem. Hold the end of the valve stem, and use the valve stem removal tool, to tighten the center pin in the valve.
Seat the tire in the rim. Use an air compressor to inflate the tire, by placing the air chuck of the air compressor hose over the new valve stem. Hold onto the end of the valve stem, as the tire inflates. Once the tire is inflated, air pressure will hold the new valve stem in place.
Check the air pressure with a tire gauge, and inflate the tire to the proper air pressure. Place the cap on the new valve stem.
