They are 20s, so the setup is 245/35/20 F - 8.5J, 275/30/20 R - 9J. For 19s - Front: 245/40/19 F 19 Rear: 275/35/19 R. Those are factory setups. Also for those who think xDrive has issues with that setup, 2014 it is an N/C option to order the staggered setup.
2015 750i X-DRIVE, M-Sport, (born 3/6/2015), Moonstone Metallic, Ivory White/Black w/Honey Walnut, ARS, B&O Sound, Escort 9500ci. VO and FDL Coded.