A few of them look like a 22.5 Dayton truck rim with a plate center welded in, the rest are just regular rims designed to have a plate center welded in from the start.

I agree with John that they are far better on the road, and compared to the 11L or 12.5L's they're better in the field, too, but I think they leave a harder and deeper track in the field then a 19L does at a similar weight. I've heard the same said about the 425's or 385's or whatever the wide 22.5's are on the big trailers.

I've seen sidedress trailers up in Nebraska which had something like 14.9-42s straddling the tank carrying about 80% of the tank and a single small tire on the front.