The amount of air that needs to be added to a car tire will be based on the current inflation and the recommended inflation. Air pressure requirements vary by vehicle.
Use a pressure gauge to determine existing pressure and check periodically as the tire is being filled with air. The correct tire pressure for a vehicle should be listed on a tire placard posted on the door edge, door post, fuel door or glove box. The information may also be found in the owner's manual. Pressure can be lost during both cool and warm conditions, making it important to check tire pressure regularly. Proper tire inflation can increase the life of tires, while enhancing fuel economy.