from my tire and wheel experience over the years, i have found tire sidewall bulge can be anywhere from 1-2" per side, depending on the tire manufacturer and how big [or small] a tire tread width you mount on your wheel of choice.
in my opinion, a guy should, IF possible, try to borrow a tire/wheel combo you may be considering to use as a mock up so you can see if it will work in your application.
if that is not possible, [as said before] MEASURE, MEASURE,MEASURE !
then, figure a tad on the wide side for your sidewall bulge so you don't get any unwanted surprises.