I dunno.
No more expensive than tractor rims are, it looks to me like getting an extra set and investing in a good impact wrench (electric or air) would be a heck of a lot easier than putting these "skins" on or taking them off. You would still have to jack the tractor up. Then it comes down to letting the air out, wrestling the skin on and airing the tire back up OR zipping 5 or 6 bolts off and back on. If the "skin" is pliable enough to get over the ag tire, how is is going to hold up? Go grab an unmounted turf tire and see just how much (or little) give it has. Seems to me it would be a pretty big challenge to slip that over a ribbed bar tire, particularly after you mold in the pattern of the bar tire inside so that this thing actually has some traction.
But, hey, people told Edison that oil lamps work just fine, too!
I am not accusing you of trying to re-invent the wheel or anything, but..... /forums/images/graemlins/grin.gif