I am no expert by any means but (and I am assuming based off of the picture) that the rubbing is probably occurring on the front and back of the fender. 20" is a big wheel and you seem to be lowered practically to the max. Raising the height a little may help alleviate some of the fender rubbing, as well as shaving down the inside a little (some companies do that; I think dinan advertises some cars may need to when using their wheels). The smaller tire will help too.
You can order TPMS sensors almost anywhere, but I bought mine through Omar at velos designwerks (got the OEM ones).
2010 E93 M3 / AA Catless X-Pipe / AA Catback / AA Pulley / Vorsteiner Vented Hood and Bootlid E93 Trunk / ADV1 7.1 Wheels GB / LS3 LED Lights / AFE Stage 2 / Velos Designwerks Tune