This is something I've never paid any attention to since I have a local tire shop that mounts mine on the rim. Since I have three tires mounted on rims I decided to go out and check. The tire on the bike is very close. Of course the white dot is on the other side of the tire from valve stem, but I would say it is within about three inches of being lined up.
However the other two in the shop are probably 12 inches are so away from the valve stem. One thing I found interesting they are both mounted the same, meaning the white dot is in the same position relative to the valve stem on both tires? Not sure if that means anything?