Originally Posted by Iggy
Michelin 235/80/22.5 possible?
These tires are 32" diameter
The formula we use to approximate tire diameter with metric width/aspect ratios in the tire biz is as follows. This formula converts the metric numbers to inches in the process.
Using the size Iggy posted as an example:
Section width (235 mm) X aspect ratio (80% of section width)) X 2 (you use 2 to include both sidewalls height)....then divide it by 2540. There are 25.4 mm to an inch, and using 2540 fixes the decimal at this point too. You then added this converted number which will be the two sidewalls height in inches...back to the rim diameter (which is 22.5).....so you will have the approx. diameter (both sidewalls and hole in the middle)
(235) X (80) X 2 = 37600.
37600/2540 = 14.80
14.80 + 22.5 = 37.30 inches approximate diameter
This is just an approximation and can vary a little either way depending on how much tread depth and such there is. By a rule Michelins are usually just a hair shorter than other brands, with the same size.
32 inches would be way too off though, if my math is correct.