What is Indirect TPMS? What does it do?
An indirect tire pressure monitoring system works with the vehicles ABS (anti lock brake system) to evaluate the tire pressure in each tire. Unlike traditional tire pressure monitoring systems, an indirect tire pressure monitoring system uses wheel sensors to measure the rotational speed of each tire. An indirect system functions based on a single principle: Underinflated tires have a faster rotational speed due to its smaller diameter. Overinflated tires have a slower rotation speed due to its larger diameter.
Under and overinflation are things you want to avoid. So what happens if your TPMS warning light goes off, but your tires are inflated to vehicle specifications? There are a number of factors that can influence the rotational speed of your tires.