ETRTO agricultural correlation table

The ETRTO designations for agricultural tyres have evolved to provide better consistency between sizes and performance.
The former designation, expressed in inches, used a format such as 16.9–30, indicating only the width and the rim diameter. The aspect ratio was not specified, because most traditional agricultural tyres were 80 series. This system, still seen on some older models, lacked precision and could make matching tyres difficult when replacing them.

The new ETRTO notation adopts a more detailed metric approach, following the width/aspect ratio R diameter format, such as 520/70 R 38.
As well as indicating radial construction, it offers a clearer and more universal reading, harmonised with passenger car and truck standards. This standardisation makes it easier to compare between manufacturers, improves the identification of modern profiles, and reduces equivalence errors between different construction types.

Here is a conversion table for agricultural tyre sizes to help you navigate between the old and new notations.