I'm going contrary to the general response.
No wheels on my ironing surface. Why? Because wheels move and if they move without me intending them to move and my iron is on the board, it may fall to the floor, or worse, on me!
I can always get a new iron and new floor, but I can't get a new me!
Having said all that, I would probably raise it up without using wheels and put a couple of furniture sliders under it. Then, when I need to clean behind it, I can make sure the iron is both off and moved off the top of the board, then move it.