That is the same kind of wheel that was used on pickups with 15" wheels in the 50's. I was not aware that they had been used on 20" during the 40's. Having a Kentool lock ring tool is almost a must with these type.
http://www.kentool.com/index.php/products/lock-ring-tools/truck-lock-ring-remover-detailWe lift ring up until it just clears the wheel and then tap it with a hammer and it will jump right off. If someone tries to pry them off, they will bend. We always laid them on flat concrete ti make sure they weren't bent. Mounting them is done by prying them on It is also usually necessary to put a little air into them and tap them to seat properly. They have to be centered to seat properly They are not as dangerous as a RH-5° because you can see whats going on, but it is not as safe as the
type of lock rings that the bead actually goes over the lock ring.
I have a 41 and a 46 GMC. I have never paid any attention to the wheels. I need to go look and see what are on mine. I changed a lot of tires on 50's GM 2 tons and I don't remember seeing those type of wheel on anything larger than a pickup. But by the late 50's when I started changing tires, the 40's stuff was obsolete for commercial use.
