Maybe I shoulda titled this: The best compromises. First, there's no choice that isn't a compromise of some sort. Heck, our third gens are a compromise, being nose-heavy and the crappy front suspension design. But third gens are what we have, for whatever various reasons, and we want them to perform the best they can, where we use them, within our budgets, and most of you want them to look good doing it. The fiorst compromise is either street car versus track car, or looks versus performance. For looks, it's tough to beat the look of having the fenders full, something like a 285/40 on an 18x10. Without a widebody kit, that's approaching the upper limit of what can fit without rubbing. Plus, it's driveable in a world of pot-holes. But for performance, a 345/35R15 on a 15x14 is as excessively wide as it is overpriced. These are Pirelli P-Zeros for the Lambo Countach, by the way. Around $500 per tire.
And if you had a widebody kit, is that the theoretically perfect size for best performance? Nope. But neither is a 285/40 on a 17x9.5. Let alone a 315/35, which can but should not be squeezed onto a 9.5" wheel. Now I don't currently have the funds available to buy several sets of tires and rent Miller Motorsports Park for a day, plus I haven't yet finished final assembly of my until-now-secret LS3 stroker. You do want the widest possible contact patch, but you do want it on a wheel that's slightly wider than the tread. How wide? Well, for track use, you can stretch a 245/40 onto a 17x9.5, but you won't catch me running that on the street for 3 reasons. 1, I don't want to bend or ding my expensive forged wheels. 2, you lose most of the cushioning the tire can offer, and 3 the sidewalls are too vulnerable to various debris that might be lying on any public road.
So while you want the widest possible contact patch, the body of the car is not what sets the maximum. Nor is the suspension, nor the combination of the 2. Thise are what decides the widest possible wheel, and the wheel is what determines the widest possible tire, in an ideal situation. And it's illegal to have the wheels or tires or both out past the fenders or flares, though millions of 4x4 pickups get away with it, or I'd be running 275/40s on 17x11s on all 4 corners of my '82 Camaro. I'm not ready to go widebody yet. Oh, I just got a phone call, I gotta go. Let the debate rage here.

 

im confused, is there a question in there or whats going on? Tires should fit on the wheels, thats always a good thing, and wheels wider that than tires just look stupid.

 

you're entitled to think it looks stupid. But it works better. This is an FYI thread that I haven't had time to get to the rest of, yet.