Sounds like the tire shop was thinking about Class A tires. Class A tires, especially the 22.5" tires, are difficult to handle, align and balance, and they weigh a lot. When I had my DP Class A, I went to a truck tire shop for new tires. They were able to align the front tires and I put beads in the front tires for balancing.
Now, when you have a Class C coach, you move into the "smaller truck" sized tires, like 16", a whole lot easier to handle than the 22.5's. The tires are easier to mount, align and balance. Just about any tire shop could mount and balance them, but you might have to search for an alignment place.
Wayne Lee
Out West Somewhere
2016 Forest River Sunseeker 3050DS Class C | Hummer H3 dinghy