If your car, SUV or light-duty truck is a 2008 or newer (and some earlier models), it has a Tire
Pressure Monitoring System (TPMS) designed to alert the driver if the pressure in one or more tires
Fall more than 25 percent.
http://acdelcotechconnect.com/pdf/newsletters-press-releases/intune/2013/intune-issue-3-2013.pdf