That's the same axle setup I'm running on my bronco. My 15x8 rims (basic black steelies) have 2.5" backspacing. Ordered them with the custom bs from discount tire. Very reasonably priced, too. They clear the dual piston calipers up front with ease and the same with the rear 60. These are the best pics I could find of how far they stick out on a set of 37x12.50 mtrs...
I think the rims I have are 3.25 bs so I hope they will work getting the tires mounted today so we shall see hope it works good I'm ready to have my truck back lol