I recently purchased as set of factory TPMS sensors to fit to my winter tire set. After reading the "QP in Snow" thread, there was a discussion of rims available on Tirerack. Out of interest I looked at the rims on Tirerack and it seems that they also sell aftermarket TPMS sensors that appear to be compatible with the QP onboard system. Does this sound this correct - an aftermarket TPMS sensor for the QP? It never occured to me that an aftermarket sensor was available. I imagine the pressure is monitored via electronic signal and it would make sense that the FCC has a narrow range of MHz reserved for this application. Therefore, manufacturing an aftermarket sensor could be made for a range of vehicles.