Regarding tire Pressure, what is PSI, BAR, and kPa?

• 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) standard tire pressure reading in the USA
• KPA Kilopascal – A unit of pressure. 1 kPa is approximately the pressure exerted by a 10-g mass resting on a 1-cm2 area. 101.3 kPa = 1 atm. kPA is used as a unit of measure in Europe and other areas that use the metric system.
• BAR The BAR is a unit of pressure defined as 100 Kilopascals. It is about equal to the atmospheric pressure on Earth at sea level. 1 bar = 100 kPa (kilopascals) per square centimeter. 1 Bar = 14.50 PSI. BAR is used as a unit of measure in Europe and other areas that use the metric system.