A 275/60 is going to be taller, close to 28". Hitting the fender lip will be an issue.
Tuck them closer to the frame rail. 5" or even 5.25". You really need to measure your car, it's not uncommon for a rear to be a little offset to one side.
If you don't have enough clearance on the inside, you can always shim the wheel out a little with a wheel spacer.
But if you are lacking clearance on the outside, there isn't much you can do except for trimming or bending up the fender lip.