What size offset would I need to fit a 17x9 wheel in the front with Stance GR+ and without rolling the fenders?

 

It depends, if you want to run tires that fit the rims properly, such as 245's, then it probably can't be done. If you're wanting a stretch with 215's or something, then that's another story, you'll have to be more specifi.

 

Maybe run a 225 stretch?

 

here, check this out... should give you some ideas
https://www.rx7club.com/showpost.php...&postcount=440

from this thread
https://www.rx7club.com/shineautoproject-161/fc3s-vent-less-frp-wide-fenders-590413/page11/

 

I was hoping to have them just fit without any modification...

 

Well then you should go with narrower wheels. There's just not that much room in the front.

 

Ok, that's what I was expecting. Just wanted to clarify.

 

if your just going for the look, then streching the tire and running more then spec camber should get it under the fender

 

You could do that, but then you'll suffer from reduced front end braking grip and maybe even reduced cornering grip, plus the tires will wear out faster and you'll be constantly running the risk of rubbing.

For comparison, 17x8, 30mm offset wheels will fit nicely and a 225/45/17 fits nice and squarely on it. That's what I've got and with 3 different sets of tires now on stock suspension and coilovers and it's never rubbed.