Example: 235/70R15
235 = Section width in millimeters
70 = Aspect ratio (ratio of section height to section width)
15 = Rim diameter
R = Radial Construction B = Bias Construction D = Bias Belted Construction
To calculate:

Tire Width: Section width divided by 25.4 (Ex: 235 / 25.4 = 9.25″)
Section Height: Tire width times aspect ratio (Ex: 9.25″ x 70% = 6.48″)
Overall Diameter: Section height times 2 plus rim diameter (Ex: (6.48″ x 2) + 15 = 27.96″)
Therefore, a 235/70R15 is approximately 28″ tall x 9.25″ wide.

IMPORTANT
There are many variables that affect a tire width such as rim width, air pressure, sidewall constructions, etc. just to mention a few. Please feel free to use these charts as a guide only. If you are trying a custom fit and our tire looks like it may be a tight fit, contact the M/T® Tech Department and we will be happy to help you with your fitment issues