Surely we have seen colored dots on the sidewall of the tires at some point. Not only in motorcycle ones, but also in automobile ones. It is usually common to see these colored dots on the factory mounts, that is, on the tires that come when we buy the motorcycle. But it also happens, sometimes, when we install new tires.
The first thing you might think is that those colored dots are some type of marks derived from quality control or similar. Nothing could be further from the truth. Its function is to mark certain characteristics of the rubber and, at the same time, facilitate their mounting on the rims.
The function of colored dots on tires
Tires can have none, one or two colored spots. If you have one, it could be red or yellow. And if you have two, it will be one of each color. Each one has a different function, but in all cases it means the same. It is standardized for all manufacturers.
When a tire is manufactured, despite high quality standards, it is impossible for it to be perfectly round or perfectly balanced. In this way, the manufacturer will mark the lightest point of the tire with a yellow dot. Likewise, the red dot will indicate the lowest point of the tire, or in other words, where the radius will be smallest. Be careful, it will be by tenths or thousandths, otherwise we would have a rugby ball.
In this way, when tires with these colored dots are fitted in a workshop, the technician will align the yellow or red dot (if there is only one) with the valve. If both are present, it is normal for red to be priority, so this will be the one that is aligned with the valve.
Why the valve? Because in most cases, this is the point where the tire weighs the most. The entire valve system and its anchoring is heavier than the small loss of material involved in making the corresponding hole.
Thus, when the tire is mounted correctly (its correct name is the English word matching, match), the amount of weights for balancing will be minimal and, in most cases, it will not even be necessary to put any, leaving the tire/rim assembly perfectly balanced.