" The tread width and tire carcass is about 1-1/4" wider on the 235 than the 225."

Might help a little. The point I was making was that the new 225s I put on are about 1-1/4" narrower than the 235s they replaced, not 10mm that I thought they would be. I'd have never thought this would be the case because the dimension is supposed to be a physical dimension. I cannot explain.