I had a friend tell me they were based on the ABS sensors but this doesn't sound right. Anybody know if they've got the RF-based sensors or not?
Yes, they absolutely do, and my left front is beginning to annoy me. Door sill claims 30 lbs pressure. If I forget to tell the shop to run me up to my standard 33, they set at 30. Drop that bugger just 1 pound to 29psi and off it goes. Doesn't have the margin that the others have. I'm more accustomed to them going off at 25psi or so. The ones in my 300M are rock solid and reliable enough to give me true psi readings on all 4 corners (not just idiot lights). Saved my butt once when I left a shop with one tire at 45psi after rotation. They forgot to relieve the pressure after the mount!I had a friend tell me they were based on the ABS sensors but this doesn't sound right. Anybody know if they've got the RF-based sensors or not?
Yes - they are individual RF transponders on the stems on each tire. The Hyundai system (at least thru '09) is kind of pain in the neck in that the "computer" for the TPMS can't remember 8 different sensors, so swapping a set of winter rims kinda blows up the idea of a TPMS equipped winter set. The dealer has to initiate a reprogram if you want to do that.So yes they are RF based?