[jagarra]

I have the same rims on my truck. They are 3 pieces rims rather than the conventional split rim where there is a break on the outside piece. I change them myself but I have a manual tire changer. Had to rig up a plate, then blocks of wood to apply pressure on the edge.
I order to get to the locking ring which is located below the outer edge of the rim, the otter edge has to be pushed down past the locking ring, then the ring comes off with a large screwdriver or tire bar. then the whole tire and tube can be removed as a unit.
You may have a difficult time finding someone to do this, don't know where you are located to give you any assistance.
Once the tire is deflated getting the rim edge down is the trick, you would have to rig something up to push the rim down then it's pretty easy.

Saw that you were in NY, so helping out won't work. Maybe 2 big C clamps or bringing a weight down on the rim with equal length blocks between the weight source and rims