I was looking at some other cheap tires to put on this car, and came across something I was considering for the front. What'* the maximum width tire one can put on a GXP rim?

Here'* what I glanced over for a second, and was curious about:
4 Used Pirelli Super Sport P7000 265 35 R18

That'* a really wide tire. I've read about members rubbing with 255s, I think a 265 you can count on that. As well as risking hitting the fender flare on a hard bump.

Alright, thanks. Would a 245 tire work?

I would love to see some pics of the new stance with the 255'*.

I used to own a 1994 corvette and swaped the rims(different offset), stock was 285'* and went to 315/35'*, What a difference!

I'm running a 245/45R17 on my car with no problems at all. This tire is about 1" wider then stock, and 1" shorter then stock. I'm sure I can get a 255 on. It really depends on the offset of the wheel. But pulling the wheel out to avoid rubbing, you start to move out past the edge of the car and the tire can hit the fender on a hard bump.

If it is shorter in overall circumfrence ,Than you may have an incorrect reading on you speedometer.

although you probably know this already, the sidewall height is a percentage of the width, so if you were previously running 16" with a smaller width and higher sidewall, its possible it came out even

Yes, I'm off by 3.8% so about 1 MPH for every 25 I'm going. It'* easy to figure out

The '04 and '05 GXP have a collar on the strut that practically hits the tire at 235. without an offset rim, I think the 245 would hit, a 255 impossible.