Tire sizes and offsets

Can anyone tell me the original wheel and tire size and the proper wheel backspace.

 

[Bob Putnam]

Which "original" vintage GT are you asking about? Wheels grew considerably as the car was developed.

 

I guess I would do the later ones. Im wanting to start doing some chassis design work. Im planning on designing my own spindle but I need to first get the tires and wheels or at least the correct sizes before I start designing the suspension geometry.
What seems to be the most popular sizes and offsets. Who is building the best wheels ??????