When I bought these wheels with my FBI fat tire rear end for my 06RG, I had no idea what a problem they would be with mounting a tire.
The wheel doesn't have much of a center well like other wheels do. When installing a tire, ya have to put the bead of the tire into the well in order for the tire to extend past the rim on the other side for it to go on.
I can push the first side of a tire on a stock Harley rim pretty easy then us a tire iron to slip the second edge over the wheel rim because the well is deep enough to push the tire into.
The RC wheel has such a shallow well, its like tryin to slip the tire over the wheel with the edges of the tire on the bead.
Prior to now, I always had a shop install new tires. When I had a shop install my car tire on the back wheel, I couldn't get them to put some effort into it to stop the air leak at the bead. I bought my own Harbor Freight tire changer stand and can do them myself.

 

I've been doing some research on mounting my own tires recently and saw some YouTube of kids using straps and zip ties to squeeze the tire edges together for mounting without tools. Maybe you can use a similar technique to the tire into the well?
Just thinkin ...