Newbie question about wheel/tire widths
 

Hello gruppe,
I'm sure this question has been addressed before, so please forgive me for repeating. We recently purchased a 2013 X6M. Although it came with the nice Motorsport OEM 20" staggered wheel and tire setup, I'm looking for something a little more aggressive. I'd like to upgrade to a 21 (or 22?) inch setup. Is there a thread for optional wheel and tire combinations?, or anyone with opinions/suggestions, or anyone with a set for sale?
Thank you in advance.-Wil