There can be two dots. One for the highest out of round location and one for the lowest weight location. No standard on this and no objective information. Might be used by OEM's when they assemble tires on rims at the car factory.
Different manufacturers use different color dots for various purposes. There is no standardization in that respect.
Originally Posted By: wemay
I thought it was the heavy side and should be positioned opposite the valve stem. At least that's how Wheeler Dealer's Ed China explained it.
NOT this ^^^
It's the out of round high spot of the tire (SOMETIMES marked by a red dot) that is supposed to be matched to the out of round LOW spot of the wheel (that is SOMETIMES marked by the valve hole) to get the roundest assembly possible. It is NOT about reducing the amount of weight needed to balance!!!
Yokohama puts 2 dots on their tires, one for lightest spot and one for out of round. Since my snow rims didn't have any markings for out of round, they just mounted the tires with the lightest spot at the valve stem.
They didn't take much weight to balance them this way.
Most of the time it doesn't matter. You would need to know where the heavy spot on the wheel is. With a TPMS sensor you would assume that would be it, but some wheel are counter weighted to compensate. Also you have know idea how light the wheel is where the dot is. Is it 1/4 ounce, or 3 oz?
If your tire manufacturer follows this protocol:
"When performing uniformity match-mounting, the red mark on the tire, indicating the point of maximum radial force variation, should be aligned with the wheel assembly's point of minimum radial run-out, which is generally indicated by a colored dot or a notch somewhere on the wheel assembly (consult manufacturer for details). Radial force variation is the fluctuation in the force that appears in the rotating axis of a tire when a specific load is applied and the tire rotated at a specific speed. It is necessary to minimize radial force variation to ensure trouble-free installation and operation. Not all wheel assemblies indicate the point of minimum radial run-out, rendering uniformity match-mounting sometimes impossible. If the point of minimum radial run-out is not indicated on a wheel assembly, the weight method of match-mounting should be used instead.
"When performing weight match-mounting, the yellow mark on the tire, indicating the point of lightest weight, should be aligned with the valve stem on the wheel assembly, which represents the heaviest weight point of the wheel assembly. After match-mounting by either of the above methods, the tire/wheel assembly can be balanced."http://www.yokohamatire.com/tires_101/tire_care_and_safety/match_mounting/
My new Kia had green stickered dots on the wheels, and the Kumho tires had their red dots aligned with the wheels' stickers. I marked the wheel dots with a rounded center punch when I removed the stickers. When I had snows installed, I put masking tape with red arrows at those spots and told the tire guy to match the tire's red dots with my wheels red dots. He was mildly impressed. Anyway, only two of the snows had red dots, they were mounted so they lined up, and the tires run smooth.