i asked a similar question on the tire rack blog and got this reply:
Thursday, October 25, 2012 by michael:
I have 225/45/17 winters on ASA rims from my 2007 335 that I would like to use on my F30 335xdrive. I don't need the sensors because I'm in Canada. Can I use them on the F30 and what will the downside to using 45 profile tires instead of the recommended 50?
Thursday, October 25, 2012 by Gary:
Yes, you can use the shorter 225/45R17 size on the new F30. The tires are an inch shorter in diameter so the speedometer will read faster and the lower profile tires ride more stiffly than a 225/50R17. You should run the tires at 36psi or higher to maintain the proper load capacity.