In 1898 George Schrader patented a valve that bears his name. A Shrader valve is located in every valve stem used on car tires. The only way to deflate a tire is to use the valve stem, but there are three methods of doing so: depress the Schrader valve, remove the Schrader valve or completely remove the valve stem. The last option generally is used when purchasing new tires and replacing the valve stems at the same time.
Remove the valve stem cap and depress the Schrader valve using the reverse side of a tire pressure gauge. A small, metal protrusion is designed to depress the valve and allow air to escape.
Unscrew the Schrader valve from inside the valve stem using a valve stem removal tool, which is widely available at auto-parts stores. Insert the forked end of the tool over the top of the valve and twist the valve to the left. As the valve unseats, the air will escape. Completely remove the valve for tire service.
Pull the valve stem out of the wheel and allow the air to escape using a valve stem remover tool, which is available at auto-parts stores. Screw the end onto the threads normally used to secure the valve stem cap. When fully secured, pull the stem sharply to pop it out of the wheel and air will rush out.
