Tires: Tire Pressure Sensors, tire pressure sensors, model cars

Question
On some newer model cars, there is a dashboard warning about low tire pressure.  Yet, there is nothing obvious on the tire that senses the pressure.  How does this work?

Answer
Hi Chad,

These newer models that have the tire pressure sensors are located under the valve stem inside the rims,Becareful if you wanting to check one to see it's bad or the batteries are going bad or you will easily break it and they cost almost between $28.00-75.00 a piece to replace. The sensor monitors the air pressure since half of the drivers today don't check there tire pressure and that is why there is alot of tires wornout due to underinflations and Genereal Motors brought out that idea. Hope this helps