Center Line Rims and tires

I have two Center Line rims 15"x8" by 5 on 4 1/2 bolt pattern with lugs and 5" back space, 5" from where axle flange meets to outside of rim, with almost new Firestone tires 275/60R15 for sale. one tire has a plug in it, but does not leak. I bought them to put on my 1970 Duster but the tires are to close to springs (1/4") I would like to get what I paid for them $250.00 or trade for ? I added picture of back space being measured and Center Line stamp

100_0955.JPG

DSC00028.JPG

DSC00036.JPG

DSC00037.JPG