On a 17x9.5 rim, can I run a 285/40 on the back and a 255/45 on the front? Does anyone have this combination and does it rub or affect performance? If I can't run these size tires, what's the max I can run on a 17x9.5?

 

Yes, you can run the 285/40. That size came stock on quite a few Corvettes with the 9.5 inch wheel.

The 255/45 size on a 9.5 inch wheel looks just a tad funny.
It will work just fine, but tire bead looks to be wider than the tread.
My '96 came stock with 255/45 front tires, but the factory used an 8.5" wheel on the front of those cars.

So, I went to a 275/40 on the front when I went to the new 9.5" wheels. It looks a lot better.

 

I was more worried about the 285 on the back, but thank you very much, you've been a big help.