How do you calculate the size of a tire?
How do you calculate the size of a tire? Here is the basic formula: Tire Diameter = 2 x (section width/25.4) x (aspect ratio/100) + rim diameter. When you plug in the values from our sample tire, the formula looks like this: Tire Diameter = 2 x (235/25.4) x (60/100) + 15. How do you compare tire size? To compare tire sizes, first select your vehicle stock tire size. Immediately available tire sizes that are with in plus or minus 3% variance will be displayed. Select the tire sizes to compare to your stock size and click 'Compare Selected Sizes'....