The tire load range lettering system is the official method for identification and displaying LT & ST tire load capacities. They are standardized and work “hand & glove” with load inflation charts for all ST & LT tires.
In the example below you will see how a manufacturer labels a specific tire and its load range. The load index system, also present on the example is there for a single purpose; to display the tires speed letter rating (L = 75 MPH). The 14 PR is just that, a tire strength equal to a true 14 ply tire (cotton).
Sailun S637 label.JPG