Hookless rim pressure limits
Hookless and tubeless straight-side road rims have a hard ceiling: 72.5 psi (5 bar). Go above it and you risk the tyre blowing off the rim. Here's why the cap exists and how to stay under it.
Why 72.5 psi?
Hooked rims have a small bead-retention lip that mechanically locks the tyre to the rim. Hookless rims rely on a tight tolerance between the tyre's bead diameter and the rim's seating diameter. ETRTO (the European Tyre and Rim Technical Organisation) sets the standard at a maximum 5 bar / 72.5 psi for hookless road systems to ensure the bead stays seated.
If your calculator number is over 72.5 psi
- Don't over-inflate. The bead is the failure point, not the casing.
- Fit a wider tyre. Going from 25 to 28 mm typically drops the required pressure 10–15 psi.
- Check the rim's own max. Some manufacturers spec lower than 72.5 psi; always follow the lower of the two numbers.
- Confirm tyre compatibility. Only tubeless-ready tyres certified for hookless rims should be used.
Width recommendations to stay under the cap
| Rider weight | Minimum tyre width |
|---|---|
| ≤ 70 kg | 28 mm |
| 70 – 85 kg | 30 mm |
| 85 – 100 kg | 32 mm |
| > 100 kg | 34 mm or wider |
Indicative minimums to keep recommended pressure under 72.5 psi on smooth tarmac with a tubeless setup.
Check your number
The calculator flags whenever your recommended pressure exceeds 72 psi so you can size up before you ride.
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