The whole issue is a great example of the government mandating a technology that wasn't ready for the marketplace. After several idiots panicked and flipped their Explorer's (see the Car and Driver article from that time that proves their was noting wrong with the vehicle's stability), the politicians decided SOMETHING had to be done.The problem was, they specified HOW the system had to work (a sensor in each tire), not WHAT it had to do.

I was running a municipal garage, and had a pair of 2000 Impala police cars (tremendous POS with a laundry list of problems). They DID have one VERY useful feature: a tire pressure warning system that was just several lines of code in the ABS computer that compared the rpm of each tire. If one tire's speed increased more than a certain % over the rest (as it would when the pressure in that tire went dow and the rolling circumference got smaller)it displayed a warning to the driver. NO sensors in tires to fail. NO additional hardware AT ALL. NO EXTRA COST, EVER!! Too bad it doesn't comply with the law...