I don't have anything between my post bottom plates and the concrete, and have never seen any rust spots or stains when I have moved my lift. I guess if you had to scoot it around or drag it on the concrete it would skin the bottoms and make it rust. I have the wheel kit with mine, and it will work the same way as yours. Enjoy your new lift, and using it for work is a LOT differen than laying on your back working! You will have to figure out how to work all over again....lol.