Many tires come with a service description added on to the end of the tire's size. These service descriptions contain a two-digit number (load index) and a letter (speed rating). The load index is a representation of the maximum load each tire is designed to support. Because the maximum tire load-carrying capacity is branded on the tire's sidewall, the load indes is used as a quick reference.
This example shows you how to determine the maximum load-carrying capacity based on a tire's load index.