WHAT SIZE DRAG RADIAL SS SPRING '65 DART

View attachment 1715140233 I have been running M/T 255x60x15 on Weld Wheel 15x7/4.5 inch backspacing for 12 years or more with stock spring location and 1 inch lower caltrac mono leafs, with no tire rub at all even with 4 people in my 66 Dart

If I may ask.

How close is it to the spring?

And how close is it to the quarter?

We want to run a "regular" radial 275/60/15. And a standard 275 is almost the same dimensions as a 255 drag radial. But we're stuck between a 7" and 8" wide wheel. Both with 4.5 backspace.

Thanks. Eric