Man, that is pretty cool. I have seen those dots on tires in the past and never knew what they were for. Clearly most tire shops don't know what they're for, either!
Back in the dark ages when I was an equipment maintenance man for Armstrong Rubber Co. in Madison Tennessee tires got stamped with a blue or a yellow dot (or none at all) to indicate "conicity"- - - -the tendency of an inflated tire to pull toward one side or the other. Try to roll a cone-shaped paper cup in a straight line sometime. The tire was inflated on a piece of machinery that measured the side to side pull and stamped accordingly. People in the know about that would choose to install tires with the same colored dots on opposite sides of a vehicle so the pull of each tire would cancel the other out and avoid the vehicle from wandering one way or another. The old mechanic's tale about aligning the dot with the valve stem was, and probably still is a myth.
That was in the late 1970s- - - -things might have changed since then.
Jerry
