I've had my issues with this system. This fall I had a badly cut tire. Could not get it off the hub to mount the spare! (There's another thread about this problem) Aired tire to 80 psi, loaded my compressor and generator in the truck, and headed to the tire shop (100 miles away) TPMS light came on 10 miles away from shop, I got out just to check pressure - it was 50 psi. So even though system called for 80 psi the warning did not trigger until 50 psi. I have verified this one other time - don't ask how come!