[tkwetzel]

If that frame around the wheel prevents the wheel from contacting the diamond plate, you should be in better shape. So if that frame is below 6" tall, I think you might be ok. It is still a hard call. And it you were planning on climbing the stairs, you could use the other two wheels (probably climb better than marbled-wheels anyway).

Edit - The frame would have to be really low, because of the smaller steps.