ETRTO stands for European Tyre and Rim Technical Organisation. It is the only 100% accurate way to measure a bike tyre.

See example below for a 12" tyre
12 1/2 x 2 1/4 (62-203)

Always match the inner diameter (the second number) to your current tyre to guarantee a perfect fit on your rim.

In this example, 62-203 is the international ETRTO standard size:

  • 62 is the width of the tyre in millimetres.
  • 203 is the exact inner diameter of the tyre (bead seat diameter) in millimetres.

📏Tyre sizing

Junior Tyre Sizes

ETRTO Imperial (Inch)
47-203 12 x 1.75
50-203 12 x 1.95 / 2.00
62-203 12 1/2 x 2 1/4
47-305 16 x 1.75
50-305 16 x 1.90
54-305 16 x 2.125
47-406 20 x 1.75
50-406 20 x 1.95
54-406 20 x 2.10
57-406 20 x 2.25
47-507 24 x 1.75
50-507 24 x 1.95
54-507 24 x 2.10
57-507 24 x 2.25

Mountain Bike Tyre Sizes

ETRTO Imperial (Inch)
47-559 26 x 1.75
50-559 26 x 1.95
54-559 26 x 2.10
57-559 26 x 2.25
54-584 27.5 x 2.10
57-584 27.5 x 2.25
60-584 27.5 x 2.35
65-584 27.5 x 2.60
50-622 29 x 2.00
54-622 29 x 2.10
57-622 29 x 2.25
60-622 29 x 2.35

Gravel Tyre Sizes

ETRTO Dimensions
35-622 700 x 35C
38-622 700 x 38C
40-622 700 x 40C
45-622 700 x 45C
47-584 650b x 47
50-584 650b x 50

Hybrid Bike Tyre Sizes

ETRTO Dimensions
28-622 700 x 28C
32-622 700 x 32C
35-622 700 x 35C
38-622 700 x 38C
42-622 700 x 42C

Road Tyre Sizes

ETRTO Dimensions
23-622 700 x 23C
25-622 700 x 25C
28-622 700 x 28C
30-622 700 x 30C
32-622 700 x 32C

Shop all tyresContact us