The aspect ratio of a tire is the height of the tires sidewall, expressed as a percentage of the tire's width. It is identified on the tire sidewall as a two-digit number following the tire's section width. For example, if a tire has a section width of 215 mm and an aspect ratio of 65, the sidewall height would be 5.5 inches (calculated as 215 mm x 0.65 = 139.75 mm, which is then converted to inches as 5.5 inches) . The aspect ratio is important because it can determine how a tire looks and performs. A higher aspect ratio means a taller sidewall, which can provide more cushioning and better traction in certain situations, such as off-roading.