A load index is an assigned numerical value used to compare relative load carrying capabilities. The higher the tire's load index number, the greater its load-carrying capacity.
The correct load rating changes depending on the situation in which the tire is being used. When looking at light truck (LT) or newer Special Trailer (ST) tires, there are two load indexes branded on the sidewall, separated by a forward slash. The first number indicates the tire’s load-carrying capacity if installed on a truck with a single-wheel rear axle, and the second number applies when the tire is used in a dual-wheel application.