What Are Those Yellow Dots On My Tires?
Tire sidewalls are stuffed with tons of information. Written right there on almost every tire sold in America you'll find the size, temperature recommendations, treadwear rating, seasonal details, the date it was manufactured, how much of a load it can safely handle, the speed it is rated for, the maximum pressure it can be inflated to, its traction rating, and even the materials it is made out of.
Some of those markings, however, are a little more arcane, in that they don't actually use words, numbers, or letters. We're talking about the small dots that stand out on the sidewall, specifically the yellow ones that are easy to see even from a distance when looking at a new tire.
Keeping A Balance
To understand why that dot is there, it helps to know a little bit about how tire and wheel balancing works. Despite stringent manufacturing requirements, it's always possible that a wheel, be it steel or alloy, isn't exactly the same weight their entire way around. The same goes for tires, which can exhibit very small imbalances related to joining points or sometimes a slight difference in the circumference of one tire to the next.
To the naked eye these imperfections are invisible, but spin that wheel and tire combination fast enough and even the smallest deviations can make themselves known in the form of vibration.
To prevent that from happening while driving, every tire is put on a balancing machine after it has been mounted to a wheel. As the machine spins, it identifies the heaviest point on the tire so that a technician can add small weights to the inside of the wheel on the opposite side to bring it back into balance.
Dot Marks The Spot
Where do the yellow dots come in? The yellow dots can help minimize the amount of weight needed to balance a tire and wheel assembly by mounting the tire so that its lightest point is already matched up with the wheel's heaviest point.
The yellow dot indicates where the manufacturer has identified the lightest spot on the tire. This helps the balance technician get a leg-up on the process by matching that spot to the heaviest spot on the rim—which is almost always where the valve stem is mounted. By aligning the valve stem and the yellow dot, a wheel has a better chance of being more easily balanced.
Not Absolutely Necessary, But Definitely Helpful
It's important to keep in mind that the yellow dot / valve stem method is just a suggestion from tire companies like Nitto as a helpful reference point while mounting. It's not necessary to align these two points to ensure that a wheel and tire set is balanced, as a valve stem might not be the heaviest spot on a wheel, and the yellow dot might not always be the absolute lightest spot on a tire. That being said, the end goal of the dot alignment system is to make it easier to balance a tire, typically using less weight.
More From Driving Line
- Want to learn more about how tire balance can affect performance? We've got you covered with this deep dive into wheel and tire balancing.