Automobile tires and bicycle tires are pneumatic and require a proper amount of air pressure for smooth operation. The correct amount of recommended air pressure is labelled on the sidewall of the tire. There are times that you must adjust the air pressure in the tire. This can range from letting air out to get a car unstuck from mud or releasing air due to over inflating the tire. Letting air out of a car tire is a straight forward process. Remember to fill the tire with the proper amount of air pressure and check the air pressure periodically.
Locate the valve stem on the tire you want to let air out of. The valve stem is the stem that protrudes from the rim of the tire and has a cap on the end.
Rotate the valve stem cap counterclockwise with your fingers to remove the cap from the stem. Inside the stem there is a metal pin in the centre.
Place the tip of a flathead screwdriver over the top of the metal pin and press the pin inward. The air will begin to release from the tire through the valve stem.
Release the screwdriver from the valve stem and check the tire pressure with a pressure gauge periodically. A simple tire pressure gauge sits over the stem and indicates the amount of air pressure in the tire.
Tire pressure gauges are available at auto parts stores. If releasing air to aid in getting a vehicle unstuck from mud or sand, release about half the air in the tire.
If letting air out to help get a stuck vehicle moving, remember to add air pressure as soon as possible to the recommended pressure on the side of the tire.