I can't say what's on your truck, but GM did use multi piece rims of different varieties. My 54 had removable outer ring rims. Basically, after the tire was deflated, a flat bar would be use to pry the ring off. Anyhow, I had offers to buy them, I even thought about giving them away. MY OPINION is that multi-piece rims are unsafe regardless of the style. That's why they ultimately went to the scrap chipper.
Some folks will claim they are perfectly safe as long as you, "do this, or do that." It's true that agriculture equipment and even some commercial trucks still use multi piece rims. For myself, my wife, or my kids safety, you won't catch me driving on them. One piece rims have more than proven their worth over the last 100 years or so.
So anyway, I'm done with my rant. If your rims are 6 lug, there are quite a few options. GM is still using 6 lug rims on trucks. So, you should be able to find something. 8 lugs rims are a different story. Ford van E250/E350 seem to fit very well on these trucks. Some older GM and Dodge may fit also. Wheel Vintiques has started offering 6 and 8 lug steel wheels.
As far as tires go. Bias ply tires look cool on old trucks, but for ride and handling, a modern radial is more the way to go.
