What they said. Basically though, the only two ways to get a "deeper" looking steel wheel is to go wider and/or to build in more negative offset (less backspacing). Both of which have their own issues to deal with if you stick with certain other parameters like tire width and such.
So you can only go just so deep with the looks, before you start running afoul of the math.
There is certainly the third method, which is to change the overall shape of the center of the wheel, but that's not commonly done. Certainly not on steel wheels anyway.
Good luck.
Paul