tires parked on concrete

I just read this on another forum regarding tires. I have seen lots of discussions here saying this may or may not be true.
I figured someone here would certainly have a legitimate answer as opposed to "my wifes, third cousins, dad said".
Who knows the real answer ?

do not store your R.V. on cement. it draws out the oil in them, also can cause a flat spot and dry rot. don"t forget to check the dates on new tires.

I hope this doesn't turn into another tire brand debate. No trolling intended.