run the tread backwards for the most bite.
normal direction the tread "plows" throw the dirt like a snow plow through snow.. turn it around and it scope the dirt up giving you more traction
i would run them.. in the normal direction first... if they dont have enough bite mount them backwards and see how that does....
iirc a 2wd will run deeper then a 4wd due to having more of a heavier foot print. meaning 8000lb on one axle vs 2 axle spread over ~150" wheelbase