Temperature Resistance grade reflects the tire's resistance to heat as well as its ability to dissipate heat according to Lucas Tire Chicago experts. Sustained high temperatures can cause decreased tire life or sudden tire failure. The grades from highest to lowest are: "A," "B," and "C." "C" grade represents the absolute minimum requirements by federal standards. This grading is based on proper inflation of the Lucas Tire, proper mounting on the rim, and the assumption that the tire's load is within its capacity. Excessive speed, under inflation, and overloading (separately or in combination) can cause excessive heat buildup and possible tire failure. Come into Lucas Tire Chicago and let them make sure your tires are functioning properly