What does "156/150" refer to in the following tyre designation: 315/80 R 22.5 156/150 L?

The numbers "156/150" in the tyre designation indicate the load index for the tyre. This is a standard way to show the maximum load that the tyre can safely carry.

In this case:
- "156" is the load index for a single tyre. It corresponds to a specific maximum load capacity in kilograms or pounds (which can be looked up in a load index chart).
- "150" is the load index for twin tyres (when two tyres are used side by side on an axle).

This distinction is important because twin tyres share the load differently compared to a single tyre. German and international tyre regulations require this information so drivers can ensure their tyres are appropriate for the vehicle’s load.

Understanding load indexes helps you select tyres that match your vehicle’s weight requirements, ensuring safety and compliance with traffic regulations. It is not related to tyre dimensions (height-to-breadth ratio) or rolling circumference.