I was informed by a couple tire shops and the dealer that TPMS sensors do not necessarily read the correct/actual psi (usually they are pretty close or I would guess lots of people would complain) Or nobody checks when they inflate your tires so the TPMS reads 35psi but they had to put 40psi in to get the sensor to read what they want it to be.
Once they are off they may just need to be replaced and you still may get one or a set that are inaccurate. For example 2 of my gauges read the psi at 33psi on all tires, however, the TPMS reads about 30 in the Tahoe. I asked if the tpms could be calibrated and all of them said nope. I find this really frustrating when you want to run a lower pressure and the alarms go off because the tpms thinks they are too low. If I want to run 30psi the system thinks they are all at 27psi and the alerts go off on the dash. I was told all you can really do is replace the sensors and hope for the best. I'm not sure if this is correct but I've heard it from quite a few shops now.
Once they are off they may just need to be replaced and you still may get one or a set that are inaccurate. For example 2 of my gauges read the psi at 33psi on all tires, however, the TPMS reads about 30 in the Tahoe. I asked if the tpms could be calibrated and all of them said nope. I find this really frustrating when you want to run a lower pressure and the alarms go off because the tpms thinks they are too low. If I want to run 30psi the system thinks they are all at 27psi and the alerts go off on the dash. I was told all you can really do is replace the sensors and hope for the best. I'm not sure if this is correct but I've heard it from quite a few shops now.
