Biggest Wheel and tire Combo

[SoCal69GT]

Hi everyone, I'm new around here. I just bought my first Mustang a few weeks ago. It's a 69 convertible GT with M code engine.
I've read some posting that the biggest wheels you can get without any tubbing is 17x8 all around. My questions are:
What back spacing is required?
What biggest tire size can I get?
I'm looking at getting the Nemesis Boyd Coddington wheels. Any info would be greatly appreciated.

 

[2bav8]

I suggest you check outDodgestang's website.

He has complied a good listing of combos that people have used that actually work. I believe that 255s on a 17x8 will fit on the back, but the front is limited to a 235-245 tire.