Yeah well here's something funny, I thought I had all 15" wheels too. Why??? Because all the tires were 15". The tubes and tires were ruined so we mounted some old tires on the wheels so I could roll the thing around. All but one that is. We tried like heck to get a tire on that 4th wheel and then figured it out....
Somehow that old man managed to get a 15" tire on a 16" wheel.