CYCLE CALCULATORS

CalculatorsRim and Tire ETRTO Checker

Rim and Tire ETRTO Checker

Inner rim width and tyre width have to agree. Too narrow a tyre on a wide rim comes off in a corner; too wide a tyre on a narrow rim squirms.

Inputs

Units

Results

Widths agree
Yes

The Result is indicative and educational. It does not constitute a design, a technical opinion or medical advice and does not replace calculations or verification by a person with the appropriate qualifications and authorisations. Before purchase, installation or use in practice – in particular in electrical installations – the Result should be verified by a qualified specialist. Details: Terms of Service, point 4.

How the number is made

ETRTO 2024 tyre widths by inner rim width: 15 mm 20–27, 16 mm 20–34, 17 mm 20–57, 18–20 mm 22–57, 21–22 mm 25–65, 23 mm 28–65, 24 mm 29–65, 25 mm 29–71, 26–27 mm 35–71, 28–30 mm 47–71, 31–35 mm 58–83, 36–40 mm 66–83. 13–14 mm rims keep the older 13C row, 18–25. A half-millimetre rim, such as 20.5 mm, has to pass both neighbouring rows.

Hookless rims need tubeless-ready tyres and add their own minimum tyre width and maximum pressure. This is the width pairing only.

Related calculators

Questions

Where is inner width measured?

Across the rim bed between the bead hooks, or between the walls of a hookless rim, not across the outside of the rim.

My tyre mounted anyway. Is it fine?

Mounting is not the same as a supported width. A blow-off usually happens later, in a turn or on a hot day.

Is a 28 mm tyre allowed on a 21 mm rim?

Yes. ETRTO 2024 lists 25–65 mm tyres for a 21–22 mm rim, so 28 mm fits and 23 mm does not. A half-millimetre rim width, such as 20.5 mm, has to pass both the 20 and the 21 mm rows.

Example products

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