All BMWs have a staggered wheels setup from factory, which means wider wheels in the rear, to improve grip (as it's a rear-wheel drive car). For 1ers, stock size for 17in alloys generally is: - 205/50/17R (front) (7 inch rim) - 225/45/17R (rear) (7.5 inch rim). You can also use this neat table to see what other sizes to consider: http://www.brick-yard.co.uk/forum/tyre-size-for-rim-width_topic60146.html I hope this helps.