What are Clamp-Style Rear Wheels

I just got back from a tractor show. I took some pictures of an F40. I noticed a wheel/rim/bolt loop I am unfamiliar with. I have attached a picture. Can you tell me what it is? April 28, 2014.

These are the clamp style rear wheels. I wrote about them in an answer to a question from a guy about a month ago and in a Harry’s Toolbox article some time back about adjusting rear wheels. They were used on the early TO-35, F-40 and MH-50. John Deere and some other companies use this style wheel but not in this 24″ size.

These rims are not available from any after-market suppliers that I am aware of. If you have a bad rim on this style about your only option, if the rim can’t be rebuilt, is to switch to the 24″ loop style rear wheel or the 28″ loop style rear wheel. In both cases you will need centers to go with the loop style wheel.