too bad the government is the one saying that cars need a TPMS because people are too stupid to check their tires. i can't remember if its 2012 or 2013 all cars must have them.
also of all the tires i have replaced at the dealer the only time the valve stems were replaced was on new wheels or a TPS was broken (my school to work kids loved to do this for some reason and our tire machine sucked for them)
95% of the time you do not need new stems or sensors. the tire stores do it to cover their ass. they also make some money off of it too, $.75 valve stem and charge you $3 for.