[joedoh]

yes, they can go even smaller than that, I think min compressed height on an f9000 is 4.5". I have one in the garage for my 49, I will go dig it out and see.

they have the roll plate on the bottom to keep them from being damaged. you are supposed to have/put a 5" diameter bottom mount/plate under it, and there will be no damage from it hitting that mount/plate. the only thing it is doing is rolling onto and off the plate, there is no rubbing.

edit, 4.5 is what firestone says for compressed height