The shoes are to set height. I used shoes when I had a gravel driveway and set it for blade a 1/4" up. When we moved to our new house with concrete, I set them even with blade. Your blade should have a wear part on it, that you replace when need too. Hope this helps.

 

I never use the skid shoes on concrete. I did add a 52" long X 4" wide X 3/4" thick piece of rubber mat behind the ware bar. It hangs about 1/4" below the ware bar, that is what is riding on the concrete when plowing. I didn't want to take a chunk of concrete out of the drive way. The mat is a horse stall mat that you can pick up from any tac store think it measured 4 feet x 8 feet for $40.00, cut off what you need and use the rest for the horse stall or padding in front of your work bench. When it wares out cut another piece off.