Here are the formulas with some examples:

1.Section width: To convert from millimeters to inches, multiply the given mm by .03937, For example the stock section width of a WS6 tire is 225 mm's So 225x.03937=8.86 inches. The section width is the widest point of the tire, not patch.

2. Section height: First you need to find sidewall height. This is done by dividing the section width by 25.4: 225/25.4=8.858 inches.

Then multiply the overall sidewall height by the aspect ratio: 8.858x.70=6.2 inches.

Then to get overall size multiply the sidewall height by 2 (top and bottom) and add rim diameter: 6.2x2+15"= 27.4 inches.

So let's plug in some others.

255/60x15:

255/25.4=10.04 inches.

10.04x.60=6.02 inches

6.02x2+15=27.04 inches overall tire height.

245/60/15

245/25.4=9.65

9.65x.60=5.79

5.79x2+15=26.58 inches

235/60x15

235/25.4=9.3

9.3x.6=5.6

5.6x2+15=26.2 inches

Here is the 235/60 15 on my T/A

Here is the 255/60 15 on my T/A