Referring to the widest point of the tire, from sidewall-to-sidewall. Usually measured in millimeters, the larger the number, the wider the tire.
The rim size, measured in inches, is the distance measured between the two bead seat areas in a tire, where the tire and the wheel come together.
The load index refers to the maximum weight a tire can carry when inflated to the correct pressure. The load index number corresponds to a maximum weight on the Tire Load Index Chart.
Based on a speed rating chart, the tire speed rating refers to the fastest speed that the tire can safely maintain over time. With higher speed ratings, you will experience better control and handling at higher speeds.