I got the bigger base plate lift as well, because I only have 6" of concrete as well and the smaller lift has a smaller floor plate. I figured the more distributed the weight is the safer Id be. Honestly its ok for cars and maybe half ton trucks but 9klbs, I dont think so. Lol, i put my 06 crew cab long bed 4x4 dually duramax on it, just to lift a few inches to do a tire rotation, scary to say the least, and thats a few lbs under 9k. Seems to me they should be underrated not overrated.