Interesting on the suspension bumper. Didn't know that. Is that available aftermarket? So that means the height of the tire is the problem, not so much the width I assume. My car will have both heavy duty torsion bars and anti sway bars so I'm thinking that may limit the wheel travel quite a bit.

Yes, the G-60's would fit the wheels that came on the car, but 15 x 8 was not a wheel size option, at least to my knowledge.