I don't like going down the well beaten path, so I'm running 4 of these, 235/55R17 99W Firestone Firehawk Indy 500, from TIRE RACK, and I am very happy with them. They're summer tires, sticky in the dry with excellent wet traction. Believe me, in Florida, wet traction and hydroplaning resistance is critical. I have experienced conditions that prove out the MFG claims many times over. Summer tires have shorter tread life than all season tires. Mine are a year old, and no noticeable tread wear without a measuring device.
The above tires were installed after the picture below was taken. Shown in the picture are all season Firehawks on the rear and nearly worn out generic tires on the front.
I have those rotary shaver wheels on my 2005 GT from the factory. I would not try and force any wider tires on those wheels than 235/55 17's simply for the sake of looks. It's not worth the extra money, and you won't fill up those airplane hanger wheel wells much better. And besides, they will look stuffed on anyway. Also, you need to stay within 0.25 inches of the 27.2 inch +- design overall tire diameter.
For wider without the weirdness of too flexy sidewalls, you'll want to go to at least 9" wide wheels on the front, and 10" on the rear with tires sized to fit and within the tire diameter programmed into your speedometer. Then, you'll be way closer to the fender lip.
130 total pounds of Pitbull ruled by 8 pounds of cat.