Tech Bulletins

 

DICK CEPEK METRIC CONVERSION CHARTS

DETERMINING THE AGE OF A TIRE

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 Dick Cepek Tech Department and we will be happy to help you with your fitment issues.

This is Dick Cepek General Technical Bulletin #4.
Revised 6/30/09
For more information regarding Dick Cepek Performance Products
Website: dickcepek.com
E-mail: tech@dickcepek.com
Phone: 330.928.9092