Motorycle Tire Size Guide

Do you know how to decipher those numbers on the side of your tire? or do you know how to go 1 size wider or 1 size higher on choosing your new tires? In the Philippines, motorcycle tires are commonly sized using Metric, Inch. The other one is Alpha which i wont be discussing since it is not common in here.


motorcycle tire symbols fdr

In the photo the size of the tire is 100/80-14 48P. This Means:

-The tire is 100mm width.
-80% of 100mm sidewall height =80mm.
-Bias construction
-This is for 14 inch rim diameter
-referring to the chart can carry 180 kg and can run up to 150km/hour


  • Section Width – The section width is the width of the tire in millimeter. So when you haFDR tire chartve a 100 for the section width then it is a 100mm wide tire.
  • Aspect Ratio – Aspect ratio is the height of the the sidewall of the tire in Percentage of the Section Width. Example: In the Photo you have a 100/80 – 14. This means that your sidewall is 80% of 100mm and is equals to 80mm. What if you have a 90/80-14? well just multiply 90mm by 80 percent. This is equals to 90 x 0.80 = 72mm.
  • Tire Contruction – This can be Radial or Bias construction. I will explain this in another article. Commonly has 2 symbols the Dash(-) for Bias or the letter “R” for radial.
  • Rim diameter – The diameter of the Rim in Inches.
  • Load Index – This number is a symbol and you must refer to a chart. The load index is the safe maximum weight the tire can carry. For this tire the Load index is 48. Referring to the chart It can carry upto 180kg.
  • Speed Symbol – The safe maximum speed the tire can go. You must also refer to a chart so that you will get the values for this. Speed Symbol is P. Referring to chart it can go up to 150km/hr



In the photo of the tire the size of the tire is 100/80-14 48P.

-The tire is 2.75inch wide
-The aspect ratio is at 100percent. This means height is at 2.75 inch
-Bias construction
-This is for 17 inch rim diameter
-Load index is 41
-Speed symbol is P

In the INCH tires dimensions, the section width is measured in inches. The Aspect ratio is always at 100percent. This means the width is the same as the height. Reading Tire construction, Load index, speed symbols are just similar to reading the tire symbols on the metric system. You still need a chart. Ply Rating is the number of ply the tire has. 4PR means it has 4 Ply. The  higher the number of ply the thicker the tire.



Post navigation