Which X's 215 wheels are you looking to get...the E70 X5 or e71 X6? The e71 is one of the oddball BMWs which has a split axle hub size. The front has a 74.1mm hub and the rear has a 72.56mm hub. To fit the rear wheels from an e71 doesn't require anything extra...but the front wheels (with the 74.1mm hub) will require a wheel spacer or hub centric rings to make up for the wheel's larger center bore (just like all 4 215 wheels from the e70).