Because I have this much flood water in my backyard, and with only 9" I couldn't even get to the deep part! The ground underneath was still solid so traction wasn't a problem, I just idled through. The fan blade was hitting the water (this sounds horrible) and I don't have a dust sheild on my torque converter so it was throwing water out from under the truck. I have a 3" body lift and the floorboards were level with the water, so you can imagine what all was under water. The tires are 38.5 Hawgs.