It's the height of the sidewall measured from wheel rim to top of the tread, expressed as a percentage of tire width. In this example, the aspect ratio is 65, meaning the sidewall is 65 percent as high as the tire is wide. To get the sidewall height, take the tire width of 215 mm and convert it to inches (8.46).

How do you calculate side wall height?

The sidewall height can be calculated by multiplying the ratio (70 or 0.70) by the width (225): 225 millimeters x 0.70 = 157.5 millimeters. The number 15, or R15, is the diameter of the wheel (or rim) given in inches.

How does sidewall height affect performance?

As tyre sidewall height decreases, performance tends to get sharper and handling usually improves too. ... But this can all depend on the brand and type of tyre you put on your car too. Larger wheels can impact on ride quality making for a skittish, more thrashy driving experience.