widest tire and back spacing?

[RAL239]

I have a 1974 Satellite and I cant find anything on back spacing or tire size. Im wanting to run 17x7 up front and 17x10 in the rear. what type of backspacing do i need and whats the widest tire i can run on a 10in wheel without modding my vehicle?

 

[benno440]

usually about 5" backspacing for a 10" rim with a 295 tyre before mods but best thing you can do is buy "percy's wheel rite" tool it bolts on where you wheel goes and you can set it at different measurements and it will tell youthe biggest you can go.
i think it cost me $120 and has already paid for itself