I think you have answered the question yourself. I have the 18s or whatever came standard on my non sport 4.8. I had aftermarket 20 inch wheels on my former truck which was similar in size. 20s are totally acceptable on a daily basis provided you are ok with sacrificing a little comfort for beauty. Really for me it comes down to hitting potholes in the road etc If you live in an area with smooth roads I would not think twice about going 20s plus. This is no s600 after all. The x already has a firm ride so I feel there is less to lose. good luck with your new x
