THreshER 7

I have read over the tire fittment archive, and didn't really find what I was looking for. I have an 86 GXL that is currently having the RMagic reproduction 8 piece racing wide body kit installed on it. The front fenders are 1.5 inches wider, and the rear is just shy of 2 inches wider. So, how wide of a rim can I run front and rear? On the rear I am looking at a 15x12 or 10" Aero rim (NASCAR rims) on a 5" backspace. I have a choice of 15x8 or 10 inch rim up front on any backspace needed to install them. Any backspace selection is available. For the front, what is the best backspace to fit the rim properly? Is it still 5" backspace? I haven't been able to locate a wide selection of tires for this rim. Especially the 15x12. I was looking at the 295x50x15 for the rear. (widest 15" I can find so far) That would fit the 10 inch really nice. It would be 26.4 inches tall, which should still fit the fender well.
If anyone has any experience or suggestions to set up the proper fittment, I would greatly appreciate your thoughts!!

Thanks,
Troy Fitz.
Get Nervous Racing