I have 12mm front and rear with stock 19" wheels and H&R springs. The rear tires rub anytime I have people in the back seats. It's not noticeable when driving in that I don't hear any rubbing, but when I look at the tires (after recently applying tire dressing on them) and I can see the rub marks. Probably wouldn't rub with stock springs but 12mm spacers definitely cause the tires to rub the rear fenders when the suspension is compressed enough. I don't know how some of the other guys get by with 15mm or greater rear spacers with stock 19s. The only solution I can see is to shave off the plastic fender liner (it rubs on this, not the actual metal fender).
2012 R35 GT-R (559whp)
2008 E90 M3
2007 E92 335i (369whp, 354wtq) sold
2004 G35 Coupe sold