245/60/15's on 15X8 rims

My 69 Swinger with all new springs, bushings, hangers, shackles, and shocks will not take a 255 60r15. I have a stock width sbp 8 3/4. I had 245 60 r15 on 15x8 with 4.5 BS and it was very tight and often rubbed on passenger side wheel lip. I then switched to 235 70r15 which are also very tight. I currently have 15x7 with 4.25BS being painted. This car has never been wrecked or bent it just has tight wheelwells. Blanket statements like "THIS WILL FIT YOUR CAR" are risky. Our 71 Scamp has more room than my 69 Dart, also has sbp 8 3/4.