Originally Posted by neejkoob
I think stock 325XI with sports package has staggered 225/45-17 in front and 255/40-17 in rear = difference in overall diameter between front and rear = 0.06 inches or 0.24028 % difference
235/35-19 in front and 275/30-19 in rear = difference in overall diameter between front and rear = 0.02 inches or 0.07849 % difference
I think this is even better than stock set up
It also varies slightly with tires. As an example I have Kumho MX's on my carrera at 225/45/17 f and 255/40/17 rear. The tires from the mfr are exactly 25.0 diameter both front an rear.