OK, so now I've decided that incorporating a wheel into the middle of the skid is a great idea, but is cast iron the right material for my wheel? Fact is, I'm not only trying to make my life easier... but I'm also aware that by rolling over the surface, I'm not damaging the surfaces any more. I learned this by talking to some contacts I made at Ariens. (Great folks by the way!) They informed me that equally important, the roller-skid design I was working on would protect surfaces. This was becoming increasingly important with all the stamped, decorative concrete driveways and walkways out there. Back to the cast iron wheel. I found that the cast iron wheels still scratched my concrete when turning through corners so I became more convinced that a Nylon wheel was the solution. Even though it would be necessary to replace them from time to time I felt it would be worth it.