I like the idea behind the 4 x 4 Labs arms but both rigs I have seen them mounted on were to tall for me. I looked into putting them on my rig and after measuring I would have had to have 5" springs with the bumpstops placed to give me about two inches from the axle. Not enough compression in my book. Maybe if you did a engine/tranny lift it would be OK but then you are moving the COG up.
Tire size will have nothing to do with clearance and at this point in time I cannot give you the spring measurement because my rig is on jackstands on all four corners.
