It has been shown that approximately 15.9 million liters of gasoline per day are wasted ($2 billion annually) in the United States due to improper tire inflation. Additionally, as automotive manufacturers begin using extended mobility, or run-flat tires, a need exists for a system which can detect an underinflated tire. We also know that underinflated tires cause premature tread wear and tear. Optimizing tire life and fuel economy are beneficial to society in general.In the passenger car market, voice of the consumer dictates: 1. Immediate notification of a low tire condition; 2. Key-on notification; 3. No interaction from driver to extinguish telltale once problem resolved; 4. Independent tire monitoring. This paper will describe a rf-based low tire pressure warning system which is being developed by Delco Electronics Corporation.