Discount Tire more than likely has never worked on a Xfire other than yours. If all tires are inflated properly (32lb) then the TPMS light should not come on, if 2 or more tires are not inflated properly and add up to 25% psi loss the light will come on. Your Chrysler dealer may have to reset your BCM, they use a special magnetic tool to reset the TPMS. Now if your Chrysler dealer can not reset the TPMS, then maybe one or more of the units are damaged, and maybe by the Discount Tire tech.