There are new innovations happening in the tire industry all the time. Something thatís been around for a few years are colored dots on a tireís sidewall.
Since it is very hard to make a tire that is perfectly balanced, some tire manufacturers apply yellow dots that indicate the tire's light balance point and serve to help you balance the assembly while mounting the tire. The yellow dots should be aligned with the valve stem on both steel and aluminum wheels since this is the wheel's heavy balance point. This will help minimize the amount of weight needed to balance a tire and wheel assembly. So usually, whenever you see a yellow dot, match it up with the valve stem.
If you see both a red as well as a yellow dot on the tire, the red dot takes priority. An easy way to remember this is the phrase ``Red Rules.'' Ignore the yellow dot and match the red dot to the wheel low point dimple as some vehicle manufacturers do or, if no dimple is marked on the wheel, align the red dot with the valve stem.
Here are a couple of references. The first is a picture I took at an RV show. The second is a tire builders PDF about the dot usage.