Here is my problem: The stairs that go down to my basement are 36 inches wide and 8.5 inches deep. I have had several people tell me that they thought the stairs were not deep enough. I have tried looking up the standard stair dimensions but I did not find anything. Can anyone offer some insight on how deep the stairs should be. And if 8.5 inches is not deep enough, is there a way I can extend the tred without having to remove the entire stair tred? Thanks in advance.