Definitely not a light duty 46, likely a 3/4 ton with that long box. Probably has overload leafs as well. Split rims are still commonly used today and tire shops use a cage when inflating after dissasembly, no big deal. I would inflate them as is to check for leaks, just stand to the side and don't squat directly in front of the wheel (you never do that anyway with splits even if they are new). Depending on where and how often you plan to drive the old girl, sometimes those older multi-ply farm tires are tough as bedrock and may still have years of life left if they were not exposed to sunlight.
