A Tyre Pressure Monitoring System (TPMS) is an automated system that monitors the air pressure in a vehicle's tyres. When air pressure in one or more tyres drops 25 percent or more below the correct pressure, a warning indicator alerts the driver. TPMS typically delivers these alerts to the driver through one of two types of warning lights on the dashboard. If you are unaware if your vehicle is equipped with a TPMS, check your vehicle’s owners manual.