If you have the cash (I don't care if you earn your money over time by selling donkeys) that you should buy a left-over new 2012 or new 2013. The standard 18" wheel Continentals are fine and aren't crappy. The crappy part runs into a production run of Goodyear RFT LS2's mainly found on some 2012's, 2011's and before. Having the right tire pressure (following full load placard) I think makes a difference.
I had a 2011 535xi that did have steering issues. Software reprogramming was done as some modification/changes to the front strut mounts were done. It was better but not perfect. I traded and got a 2012 550xi Sport Pkg. which is fine. It has none of the problems that my 535 had.
Do your research and check around. I don't think there's a large enough discount to buy used vs. buying new IMO--especially over 1-2 year old cars. You can take advantage of clearance specials, etc.