I was lead to believe the dot marks the heavy side of the tire and goes oppisite the valve but maybe the avons are even all over
cheers
Most MC tire marks locate the tires light spot. And recommend locating it at the valve stem, assuming it to be the wheels heavy spot. It's not always the wheels heavy spot. My wheels heavy spot is about 10" from the valve stems. I match up to 'my' determined heavy spot and more often then not I never require any balance weights.
With the car tire I put on I balanced my wheel sans tire, then mounted the tire to determine the tires light spot, pulled the weights, spun the tire and 0 balance weights needed to finish it out. You can do the same with an unmarked MC tire too.