Going to a skinnier tire shouldn't run into any fitment issues, however you'll generally give up some looks and handling. Wider tires have a larger contact patch and give better grip. I can already chirp the tires in a stock QX30, so I wouldn't want to give up any grip, personally. And most people think wider tires look nicer, too.1. Do you think using the same four 225/50 will be okay?
2. Are you using run flats? Ever thought about transitioning to non-run flats?