what is the aspect ratio of a tire

The aspect ratio of a tire is the height of the tires sidewall compared to its width, expressed as a percentage. Tire makers calculate the aspect ratio by dividing a tires height off the rim by its width. For example, if a tire has an aspect ratio of 70, it means the tires height is 70% of its width. Lower aspect ratio tires, such as a 60 series, generally offer vehicle handling performance advantages over higher aspect ratio tires, such as a 75 series, but a typical trade-off can be ride harshness. The aspect ratio is stamped onto the exposed sidewall of any tire alongside other numbers and letters that tell you everything you need to know about your tire.