The wheels on the truck go…
Have you seen yellow and red dots on new tires? These dots identify characteristics impacting balance of the tires. Companies which do not balance the tire/wheel assembly may use the dots to determine where the valve stem should be placed, for example. This practice places additional weight at the lightest point of the tire/wheel assembly.
The yellow dots represent the lightest point on the tire. This is typically the point you want aligned with the valve stem. The value stem will be the heaviest point on the assembly, especially if a Tire Pressure Monitoring System is present.
The red dot should be aligned to the dimple on steel wheels, it represents the highest point on the tire. The dimple on the wheel notes the lowest part of the wheel, so aligning the red dot keeps the weight balanced for the assembly. If both dots appear, use the red and ignore the yellow with steel wheels.
On all dual wheel installations, the valve stems are set 180 degrees apart to maintain a weight balance. Of course, OEs who balance tires add weight to the wheels to compensate for the material discrepancies, so the dots are a less important guide to the mounting process. The lack of colored dots is not an indicator of material uniformity.