It will be interesting to see the date code of these tires and how long they've been sitting around.
Yesterday while looking for tires for my BX22 on Amazon and eBay, a few of the tire sellers said that the date of the tire wasn't a reason for a return, and that the date of manufacturer was stated in the description. Unfortunately, none of the tires that I was looking at had date codes in the descriptions. The description was marked N/A (not applicable). Did a little more digging, and learned that the date code was a requirement of the DOT (department of transportation), and since our Kubota's are not legal for the road, the tires are not governed by DOT rules, hence, there are no date codes on the tires, and if there are, it is only because the manufacturer out of the goodness of their heart, added it to the tire.
Unfortunately, you have to work at pulling the information out of some of these sellers, since they don't give you all the pertinent information, such as the true number of ply's. Some of them say that they are 4 ply tires, when in fact, they are 4 ply rated. 4 ply and 4 ply rated are not the same. The 4 ply rated tires are 2 ply tires, and the side wall is no where near the same firmness as a true 4 ply tire.
I was looking at one 26x12-12 turf tire, and it said that the inflation was 10 PSI. At 10 PSI, I would have to leave my backhoe off of the tractor because I don't believe that at 10 PSI, it would carry the load of my tractor.