OK, well I bought a set of General Altimax RT43 Tire 225/55R17 97H Tires for my 2010 Fusion Hybrid because it seemed like the 225/50R17s had a harsh ride.
Be aware some people complained about the lower speed rated tires (T) I think as having lousy treadwear, where as the H speed rated tires had very good reviews.
The OEM Michelins lasted 40K with rotating them every 10K miles. I bought a set of Continentals AWS. very decent tire, low noise only lasted about 57K and they've become pricey.
I put the 225/55R17s on because typically one size taller doesn't hurt suspension geometry, and smooths out /improves ride quality..
These Altimax tires are nice, louder on some surfaces(mostly older asphalt and some kinds of concrete) but mostly quiet overall a very comfortable ride and no wheel opening clearance issues. In fact 3/8' diameter taller for aboput 3/4 inch taller all the way around. The ride seems less harsh suspension wise regarding feeling feeling the bumps.
I don't think anyone should have any issues going one size taller. It's when you go wider and taller you could run into issues. one size wider you might have some inner fender lining rubbing.
On my 2004 Focus ZX5 I went one size taller (no issue) and one size wider. Occasionally if I cranked the wheel really hard making a urn you would get a slight rub on the fender liner.
So that's my experience, I pretty much read the one guys suspension geometry reply and decided to try it with nice results. I measured the whel opening clearnace, checked with the manufacturer on circumference between the two tires sizes . There was plenty of room before and there's still plenty of wheel opening clearance.
Hopefully this helps others decide if they should go one size up.
