If you're still using the stock wheel tubs you should have about 12" from the quarter lip to the inside wall of the tub, give or take about a 1/4" depending on body tolerances. So if you get everything perfect, you should be able to use a tire with a section width of about 11" assuming you're not on the narrow end of the tolerance.
A 3" relocation without a mini-tub is kind of a waste of time though, you can fit just as much tire into the stock tubs with a 1/2" spring hanger/shackle offset. Even with only a 1/2" offset the stock tubs become the limiting factor.
