It's about that time again, my rear tires are all bald or chunking, and my fronts have started to show belts after last weekend. I was just wondering what the tire size consensus is, if any. For those who don't know my car, it is a 99.8% stock power 240, probably about 135hp to the ground. I'm looking at buying a set of Kumho MXs for my Z wheels and the cheapass inside of me (I own a 240 after all ) says to save $50 and get the 205/55/16, they'll be fine for my power level. Of course, i want to put the 225s on there.

...so the question i pose, would 225/50/16 make much more than a negligeable difference over 205/55/16 for my car (weighs 3000lb at the starting line, with upgraded shocks/springs) for a tire such as the Kumho MX? The followup would be at what point is the tire too wide? It seems like a lot of cars could run wider tires, but don't.