Grit dog you are correct, did not think about that 1/4" aka 0.250" in ride/axle difference
The OP, indicates he does not have a spare
If he blows a tire, he has to have road service come out and mount a new one, which he will have to buy, and thinks he won't be able to get a matching tire
I doubt he wants to buy a new tire that does not match, drive to a shop and replace with another new tire of the his brand
While you do what you have too, in an emergency, I would not want to run hundreds of miles with a miss match tire then buy another new one
Better idea to keep a new spare on hand
With the safari DP 22.5 tires, we did not carry a spare
It came without one
We drove thousands of miles with out a tire problem
Instead we spent thousands $$ on engine problems
With 3 previous RVs, we needed and used a spare tire on multiple occasions,
I don't think I would drive very far on 16 inch without a spare
One year of ownership with this RV , Ford chassis and 16" tires
And I had one flat and then the old spare blew out, a few weeks later
I have replaced 4 tires, 2 front and 2 tag and swapped the best used tires to the drive axle
The 4 on the dually drive axle are next month