^^^What width 16" wheel?
If it's a 7", a 225 will be a bit "pinched" on it, and you'll likely be better off (and faster) with a 215/45/16.
Gearing would also be better with the 215/45/16, as the 225/50/16 is one tall mother. (a hair shy of 25")
And, don't forget that bigger tire is probably going to be 4lbs heavier...
I see so many people get all concerned about wheel weight, and then they throw some tires on that are 5lbs heavier than their stock tires.
FWIW, this is what I've been running:
http://www.focusfanatics.com/forum/showthread.php?t=124065