Best tire size for Cobra R's?

[afeezor97]

Well, its been a long time since I've been here... Sold my '97 GT back in 2003, but just picked up a '97 Cobra this week so I thought I would come back to my favorite mustang forum, but allot has changed over the years apparently and this place is a ghost town. But I thought I'd ask anyway.

Best tire size for Cobra R's? Not sure if they are 17x9 or 9.5. They are already on the car, but they have 245/45's on all four corners and you can tell the tire is way to narrow for the rims. And since the tires are in desperate need of replacement, I was looking for the most recommended size for these wheels. Mainly for the front, I see stock was 255/45. I'm still up in the air on the rear. I was thinking 275/40's or upgrading the rear wheels with 17x10.5' and putting some 315/35's on the back. But I have searched around and cant really seem to find any conclusive information on wether or not they will fit WITHOUT modification or spacers of any sort. Flipping the quad-shock is no big deal, but not looking to do anything more than that. BUT if the 275/40 can fit the front without issues and I know from my GT days the 275 will fit the rear no problem, then it would be nice to have some serious corner gripping power and still maintain rotatability. But I spend more time at the drag strip than in the corners which is why I was thinking the 17x10.5 with 315/35s.

EDIT: Forgot to mention the Cobra is lowered. I think with Eibach's. Its not a lot, not as much as the Intrax I had on my GT. They were on the car when he bought it too and he don't remember exactly what the original owner said...