How to Figure Out Correct Offset?

I am running BFG 285/75R16 on the stock '04 Tacoma 16x7 rims, which I believe have a 15 mm offset. At full steering wheel input the tires rub on the frame. I want to purchase a set of 16x8 rims. Would 0 mm offset be enough to push the tires outboard enough so they don't rub on the frame? Or, would I need more like -15 mm?

 

You’d have just as much rubbing and probably even more rub with less offset and no lift. Definitely need a lift with that size if you want no rubbing.

 

I have a 3+" lift.

 

16x8 et 0 will poke a 285, 15mm more than stock.
16x8 et -15mm will poke a 285, 30mm more than stock.
Because you're changing rim width, section width of tire changes; you can't go by just the rim math.

Here's the calculator I use.

 

Interesting calculator, Splitbolt. Now, if I could enter in '04 Tacoma and they would have the fender and frame modeled.....
I guess I should have asked my question a little bit differently: "what offset rims are you Gen1 guys using to avoid rubbing with 285s?"