Rim Width

The width between the flanges of the wheel (the part the bead of the tire touches).

Section Width

The linear distance between the outside of the sidewalls of an inflated tire without any load on it (this does not include any sidewall decorations).

Section Height

This is also known as the Aspect Ratio. This is figured on a percentage of the section width. A tire size of 205/60R15 would have a section width of 205 millimeters and a section height of 60 percent of 205 millimeters.