Here's the thing with putting 275-60-15 tires on 15 x 7 inch rims...
Just because you can , doesn't make it right !!!
I know I will hear it , but that's my firm opinion !!!
Also as a side note , all factory 15 x 7 Cop style wheels , with the vent holes in them , are 4.25 backspace.
Also for that car 15 x 7 with a 255-60-15 tire fits best. Yes one side maybe tighter that the other and you may need to do some trim work to clearance everything....