I replaced the OEM Goodyears at 67,000 miles recently, and was charged $25 or so by America's Tire to "service" the valve stems. When I questioned it, they mumbled something about "replacing o-rings", etc. ... Probably not necessary from what I hear. (When they said "o-rings", I thought they were refering to the OEM Integrities )
It sounds like the manager needs to go back to school. The TPMS will trigger once any tire drops below 75% of its set point. IOW: If all tires are filled to 40 psi and SET button is pushed, if any tire drops below 30 psi, the alarm will trigger. If you set front tires @ 42 front, 40 rear: when either one of the front tires drop below 31.5 psi OR either rear tire drops below 30 psi, you will get the alert. When you rotate the tires (front -> rear), you need to adjust the tire pressures and then reset the TPMS. Since many people feel the 25% air loss is too much before getting the warning, so they initially adjust to tires to 50 psi, SET the TPMS, then let air out until you have 40 psi. Now the alert will go off when tire pressure drops to 37.5 psi (75% of 50).
darrylp - Did you replace the valve cores, and did that solve your problem? I have a similar problem in one of my tires, except that the leak is may be even slower than yours, maybe five pounds per week. It is definitely coming from the valve stem, however. I thought that when I bought new tires (which I am preparing to do once I get past the paralysis of analysis after reading all of the tire threads on Prius Chat!), my problem would be ended, but after reading this thread, I see that it will not be, so I'm curious what you discovered.
Are the TPMS the same on a 2007 and 2010? My buddy is giving me is 2010 Prius rims (they look better than the 04-09 rims) and I will like to put my TPMS on them to avoid that light or any issues. Thanks
RinMI, did you ever figure out a solution? I would recommend getting your own Techstream programmer and re-program the TPMS yourself. It'll cost about $50 to buy the adapter and software which you'll need a laptop to run on. Search for "Techstream Diagnostic Cable Mini VCI J2534 OBD Scanner V2.0.4". It has to be v2.0.4. Version 1 is way cheaper but can't program tpms.