Those pictures look like the evil two piece. Somewhere you may find RH-5 written on them. In my travels to find good rims, I found a guy that had 5 brand new ones stored away. I would not use them, they are illegal here.
Anyway. You have to break the bead and move the movable thin part of the rim inwards. After that you either lever out the lock ring, or if its an RH5, find the two indents in the thin outer rim that allow you to cock it slightly at an angle and slide off at the two short narrow points that are visible in the main rim.
The RH5 simply does not have enough interference area between the two parts and they can flex apart.
Once you have the outer bead broken, and you can get the outer rim off, its just more hard work to get the tire off.
My tires were old "Rayon" ones. Rayon is from a natural fibre and tends to rot. Also it went out of use maybe in the '60s. So if your tires are ancient and can be sacrificed, cut the sidewall all the way round, remove the maximum tire, and use an angle grinder to cut the bead from within. Then it will fall off. I wanted to keep a couple of my tires, and spent up to a full day with levers and hammers, slowly working the bead apart over the rust. And I am used to a hard days work- it was hard.
The rims can rust badly but the area around the lock rim tends to be drier and doesnt suffer so bad. I had mine bead blasted followed by heavy zinc paint.
Reassembly is just the reverse, with maximum focus on safety. The three piece rims seem pretty safe to me. Assemble the tube and rust band into the tire, and place over the large rim. Press the thin rim down and lever on the lock ring. At this point use a cage or stand the tire against a saw-horse in an open area so its vertical. Approach the tire only from the tread edge side and inflate carefully with as few PSI as possible until the tire moves out on the bead and the thin rim is loaded up against the thick rim with the lock ring in place. I use no bead lube as I want it totally dry in there. I think it is important to have a screw on air fixture- not one you hold with your hand. Keep your limbs away from the rim trajectory.
Once you have the bead up and the lock ring loaded, with maybe 5 psi in it, its done and together. Carefully inspect that the bead is right up the rim all the way on both sides. Carefully inspect the fit of the two rims and lockring all the way round. Dont get beside it, stay at the edge. I had no problem beading old or new tires. I guess the rims were a bit smaller from lost material and bead blasting.
Inflate to working pressure. Back in the day that was 50-70psi. Today you are not fully loading the truck and 35 is fine. Remember the pressure holds it together- if it goes flat it could fall apart.
At this point you can bounce it by the edges, and fit it to the truck. you may want to leave it a while, or overnight, to see if it will hold air, or blow apart.
I do not think these would blow once inflated and straight, there is way too much interference fit between the rim parts. But I was still very wary of mine.
Lastly- seal around the valve with RTV to prevent further water centrifuging in, it has no way to get out.
