Originally Posted by timcupery
Quite frequently, in mounting a tire on the rim, the tire fits rather snugly and it takes some pushing to get it all over the rim, and then the tire is unevenly tensioned around the rim. So (before inflating the tire) when you spin the wheel, you can see the tire is out of round even if the rim is perfectly in round.
I reject your premise. I see no basis for your assumption that a tire is "unevenly tensioned". An uninflated tire has to tension on it. It may sit unevenly on the rim because the bead is not yet seated.
However, tires are not perfectly balanced or true. But, unless the tire is defective, it's negligible.