Thanks for all of the input, this is what I came up with.
I first found new wheels that have the identcal look of my original 20" wheels, except they don't have the locking ring. We mounted one new radial tubeless tire and it fit the center hole and all 6 lugs perfectly. However the outer diameter of the wheel was a 1/4" wider then my original one, that made my simulators sit out on top of the wheel. My simulators were made to cover the wheel, the new wheel was visible and I just did not like the way it looked. I took my tire guy in the office and showed him this thread and asked if he could look a little more for the tire that would fit my original wheels. 2 days later he called and I brought an old tire and wheel to him and he mounted the new radial tire on my old wheel. I took it home and installed it back on my truck and everything fit perfectly. Yesterday he came and picked up they other 5 and he called today to tell me they are ready. I am going to get them tomorrow night and will install. I am happy with new safe tires. The old ones had great tread but had several weatherchecks on the side walls. My grandaughter loves to ride in the semi so I felt it was time to make it safe.
Thanks for everyones input, if it wasn't for this site I would have settled with the new wheels, (an extra $1,500 just for the wheels) Thanks again, Todd B