I just got home and looked at my wife's stock tacoma. I'd go -10 offset personally. Check out the pinch weld mod if you don't have it done. The tire will swing a bit more and contact the mud flap, the plastic and possible the pinch weld behind the front wheel.
Thanks for clearing that up for me. sounds like I'm definitely going to need to do the pinch weld mod. They don't make a -12 offset in the 16 inch that you know of do they?