A diff question about alternate tire sizes for the front of a Sport. In an entirely unscientific poll, I've noticed that the stock Potenzas already bulge over the wheel (sidewall) more than most sport-oriented cars - which makes me concerned about going to an even wider size (235/50/18) to allow more tire choice.

For best performance, should the tires be just a bit stretched, which is what I see on BMWs, Vettes, etc.? Does that deliver maximum sidewall rigidity? Or not an issue? For Pilot Sport PS2s, which is what I'll probably use, it says rim size is 6.5 - 8.5", so 7.5" stock wheels fit right in.

 

Honestly, you probably won't notice the difference in sidewall rigidity if you went from 225-50-18 to 235-50-18 assuming the same identical tire mfg/model. If you did, it would not be due to the slightly bulgier sidewall, but the fact that the 235-50-18 sidewall is slightly taller than the stock 225-50-18's sidewall.