Wheel offset and tires.

[ZomgMike]

Im planning on lowering the front of my truck even more, it tucks a little tire right now but when i cut the wheel all the way to the left or right the tires rub, so im curious as to what offset people have on their rims and what size tires. I have 235/75/15s right now. What offset should i run so i wont have any issues with rubbing in the front? I plan on doing a 4-5" drop in the front and a 6-7" drop in the back, i have a 2/4 set up right now.