Oh, and i would also go for 307 18s as they won't make that much difference to the ride (1/2" on side wall) and look a lot better (assuming you are getting RFT 17s not non-RFTs)
BMW X3 (F25) xDrive20d SE . . titanium silver . . titanium front grille . . 309s . . xline . . xenons . . black leather . . alu trim . . professional multimedia package . . dynamic package . . climate package . . electric seats . . folding mirrors . . servotronic steering . . DAB radio . . business speakers . . sun protection glass . . split rear seats . .