A tire pressure gauge is a tool used to measure the air pressure inside a vehicle's tires. Maintaining the correct tire pressure is essential for safety, fuel efficiency, and tire longevity. Most gauges display pressure in pounds per square inch (PSI) and can be digital or analog in design. Using a tire pressure gauge is simple. First, remove the valve cap from the tire, then press the gauge onto the valve stem. The gauge will provide a reading, which can be compared to the recommended pressure found in the vehicle's manual or on a sticker inside the door frame. Regular checks can help prevent issues related to under-inflated or over-inflated tires.