I have a 1979 rx7 and am looking into getting my
baby some custom rims.What offet do i need?What
is stock offset?By the way I have wide body.

Thanks,
Elliot

 

Stock offset is 18mm. Anytning above 205 or 6inch rims you need to take account of increased width to stop rubbing.

 

If you are looking for the back spacing (inner lip to machined bolt circle pad) it's 11cm.thats about 4 1/4 inches

 

is that rubbing on the fender or on the inside? and what offset?

 

a +20 offset has been known to work just fine. there's a set in the classifieds section with pix of a +7 wheel. looks to come just inside the fender.
https://www.rx7club.com/1st-generation-rx-7-1979-1985-parts-101/

 

You cannot say that only one offset works and another doesn't because offset changes with rim width. A +20 offset on a 7" wheel will fit without issue, however try and fit a +20 on a 8" wheel. Backspacing is easier to understand and more universal. 4.5" backspacing is about as far as you can go.