Originally Posted by
SweetLou
The above about it doesn't matter is correct, but there are traditional ways to put it on. Like above, quick release is on the left. If there is writing on the hub, you should be able to read it while sitting on the bike or on the right side. If the rim has a label on the side, that side should be on the right when sitting on the bike.
But only north of the Equator. Which way does your water swirl?
If you think about it, if the point touches down first when rolling forward, as the rest of the arrow makes contact with the road, it sweeps water outward.
The "tread" of the road surface itself dwarfs the tread on any road-racing tire I've seen, though. Chipseal is an extreme example.
As for the original question: as a matter of tradition & cosmetics, I use the hub labels as the tiebreaker, matching the front to the rear.