Looked up the rim part number using B8200 with 12.4-16 tire option.
Wheel P/N: 34219-27950 but this has been replaced by 66418-27950 which Messick's shows as costing $352.28 and has the description W11x16.
WARNING: The Parts Drawings shows the same wheel P/N for both this tire size and the turf option, I'd double check the P/N's!
Another option would be to inquire if Kubota Wholegoods (sales department not part department) has a listing that would work. Wholegoods would be the complete wheel/tire assembly that is ready to install on the tractor. Many times the cost of the assembly is close to the price of the tire or wheel alone. Example: Order Code ABR8764 12-16.5 Suggested List Price (2014) $330.00. This would be the complete tire/wheel/valve stem assembly ready to install. I believe the wheel sticker shown in your photo B9382 is the old wholegoods number, but this is only a guess on my part as my current tractors have similar stickers and the numbers on them are definitely the wholegoods number.
Good luck and let everyone know what you end up doing... I found a number of similar inquires as yours and they were all incomplete as to the solution.