It's not so much the diameter, it's the width. A 7.5 would be more practical than 8.0 or 8.5. As to how they'll work as a daily driver depends how low the car is, and what the roads are like in your area. I know some cities in CA that have big drainage dips at most intersections that are a real pain, you have to cross them at a 45 degree angle so you don't scrape the front airdam. Other places don't have this problem. Lots of variables here, you'll need to decide what works best for your personal situation & preferences.
