Vehicle tire gauges, and many other types of pressure gauges, are zero-referenced to atmospheric pressure, which means that they measure the pressure above atmospheric pressure (which is around 1 BAR). The following key terms may be beneficial when dealing with your gauge:
- psi (pounds per square inch) is the standard tire pressure measurement used in the USA.
- kPa (Kilopascal) is a unit of measure in Europe and other areas that use the metric system.
- BAR is a unit of measure in Europe and other areas that use the metric system and it is defined as 100 Kilopascals. It is about equal to the atmospheric pressure on Earth at sea level.
