1. Tire Width: The width of a tire is measured in millimeters (mm) and is often the first number displayed on the tire's sidewall. It indicates the distance from one sidewall to the other.
2. Aspect Ratio: The aspect ratio represents the ratio of the tire's height (sidewall height) to its width. It's expressed as a percentage and is listed after the tire width, separated by a slash (/). For example, a tire with an aspect ratio of 55 would have a sidewall height that is 55% of its width.
3. Rim Diameter: The rim diameter refers to the diameter of the metal wheel that the tire is mounted on. It's also expressed in millimeters (mm) and is usually the last number displayed on the tire's sidewall.
Here's an example: If a tire has the following markings - "205/55R16", it means that the tire has a width of 205 millimeters, an aspect ratio of 55%, and is intended to be mounted on a 16-inch diameter rim.