What is a good material to go under jack stands / ramps? yes, I know, a concrete slab. Short of that, is plywood fine? I've been using that, and it makes noise/warps/bends, but is better than just putting the floorjack on dirt. I'm thinking of getting some 3/4" pieces, hitting them with poly-something, and using those. Was tempted to get a whole sheet, but that'll be heavy and cumbersome--but would certainly be nicer than crawling around on dirt.