Whos running 275/60r15. Having issues

I have an 8.25" A body axle in my Barracuda on stock rebuilt rear suspension, leaf springs bushings ect, and I have that tire/wheel combination on my car. It works fine, I laid it all out on the computer. I had my 15 X 8 rear wheels built with 4.25" backspace as I remember. I have about 2600 miles on this combination with no sign of any rubbing inside or outside.

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The 8.25" housing is actually wider back plate to back plate than the 7.25 or the 8.75 housing. I think that is how I was able to make mine work.
So it looks like I messed up on the backspacing then. I bought 4.5 instead of 4.25. I'll probably throw some .25" spacers as suggested in a previous reply until I can get a need set of rims.
Thanks for the help guys!