Inch based identifications indicate the width in a decimal (26 × 1.75) or as a fraction (26 × 1 3⁄4), and although these size identifications can be mathematically equal, they also can refer to different size tires, which are not interchangeable.
#ETRTO STANDARDS ISO#
While traditional sizing systems are based on the outside diameter of an inflated tire (measured in inches or millimeters), the ISO standard notation uses the diameter of the wheel bead seat in millimeters preceded by the inflated tire width in millimeters. As cycling has become more global, a standardized approach was needed. The same size bike tire could be found with different numbers in different countries. In the beginning, there have been various measuring systems, with every country that manufactured bikes developing its own method of marking. Less common bike tire sizes: ISO / ETRTO (mm) ISO / ETRTO (mm)įound mostly on mountain bikes and used as a marketing term for wider 622 mm / 700C tires ISO / ETRTO (mm) Most road, hybrid, city and touring bikes. Used on mountain bikes, these tires also go by the names: 27.5+, 650+, 6Fattie, or even just "Plus tires".
Use the data from the following tables to determine interchangeability and convert between ISO / ETRTO, English, and French sizes. Nowadays, bike tires are typically marked according to ISO standard ( ISO 5775), a system originally developed by ETRTO (European Tire and Rim Technical Organization), but older English and French tire size dimensions are still used as well. Share Conversion tables for common bicycle tire sizes:
So when shopping for new tires, you'll need to know exactly which will fit your rims. Bicycle tires come in a variety of sizes, mostly depending on the type of the bike and the terrain you're riding.