zero offset should be 4.5 inches of backspacing. some people think zero offset would be 5 inches because thats smack dab in the middle but you also have to take into account the thickness of the mating surface of the wheel. most 10 rims will have 4.5 inches unless you're doing something funky like a lincoln rear in a g-body which pushes the wheels out.
So basically you're looking at 4.5" backspacing. If you runa 275-60 they will fit but I would recommend rolling the fender lips, just to keep the lip from touching if you hit any big bumps.