So here's the question: What is the widest rear tire I can run with following combo. 67 Malibu,68-72 12 bolt rear end [ 1 inch wider flange to flange than 64-67] 15x 8 inch chev rally rims. Would like to run 275 60 15  Ta's if possible. Would they fit with 7 inch rims? I have access to a machine shop where I can cut the centres out of the 8 inch rims and move them to  the the same position as a 7 inch rim. This would enable the use of the 8 inch rim in the same relative position to the wheel well as a 7 inch with the extra 1 inch width extended in towards the rear diff. I don't want to use airbags or tub the car.