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Guide
Hookless rims and tire pressure
Hookless rims are light and simpler to make, but they come with a hard limit: no more than 72 PSI. Here’s why, and which tire width you need for your weight to stay below it.
Maximum 72.5 PSI (5 bar)
That’s the limit for hookless road rims under the ETRTO and ISO standards. If your rim or tire manufacturer specifies a lower value, the lower one applies.
What is a hookless rim?
Traditional rims have a small hook on the inside of each sidewall that locks the tire bead in place, even at high pressure. Hookless rims (also called TSS, tubeless straight side) have straight walls with no hook. The tire is held only by the tension of the bead and the air pressure pushing the bead into the rim’s shoulder.
That makes the rim lighter, stronger and cheaper to produce, especially in carbon. But the hook is missing exactly when pressure is high: above a certain limit the tire can blow off the rim.
Why exactly 72 PSI?
The ETRTO (European Tyre and Rim Technical Organisation) and ISO standards set a maximum of 5 bar (72.5 PSI) for hookless road rims. It’s a safety limit with margin built in, not a recommendation. Many rim makers print it right on the rim, and some tire makers specify even lower values for certain tires on hookless rims.
Important: not every tire may be mounted on a hookless rim. The tire must be explicitly approved as hookless-compatible by its manufacturer. The rim and tire makers’ compatibility lists are binding.
Which tire width do you need?
Heavier riders need more pressure, and so do narrow tires. On hookless rims that means the more you weigh, the wider your tire should be to keep the recommended pressure below 72 PSI. The chart shows, for each rider weight, the narrowest common width at which the rear pressure (the higher one) stays within the limit.
| Rider weight | Narrowest tire within 72 PSI |
|---|---|
| 50 kg 110 lb | 25 mm rear 62 PSI |
| 60 kg 132 lb | 25 mm rear 69 PSI |
| 70 kg 154 lb | 28 mm rear 67 PSI |
| 80 kg 176 lb | 28 mm rear 72 PSI |
| 90 kg 198 lb | 30 mm rear 72 PSI |
| 100 kg 220 lb | 32 mm rear 71 PSI |
| 110 kg 243 lb | 35 mm rear 68 PSI |
Calculated with the TireDial model: tubeless, 8 kg (18 lb) bike, average tarmac, dry. Assumes a 21 mm internal rim; hookless rims are often wider, in which case one size narrower can work. If the value sits right at the limit, the next width up is the more relaxed choice. With an inner tube, pressure rises by 3–5%.
What if the recommendation is above 72 PSI?
Then your tire is too narrow for your rim and your weight. Pumping it harder anyway is not an option. The fix is a wider tire: it needs less pressure for the same load, and on real roads it’s usually no slower and more comfortable. On rough tarmac or wet roads the recommended pressure drops by about 7% anyway.
Gravel and MTB: rarely an issue
Gravel and MTB tires run at roughly 19 to 50 PSI, far below the limit. On hookless gravel rims the same rules still apply: the tire must be approved, and the rim and tire limits take priority. A more common mistake is seating the tire: a short burst of extra pressure to pop the bead into place is normal, but stay within the manufacturer’s limit.
How TireDial respects your limit
In TireDial you enter the maximum pressure of your tire and rim for each bike, so at most 72 PSI for hookless rims. The app then never recommends more than the lower value, even if the model would calculate more for your weight, and shows you that it capped the result.
Your exact pressure in seconds. TireDial uses your weight, tires and rims, tubeless or tubes, surface and wet conditions, front and rear separately, and always respects your maximum pressure. Free for iPhone.
FAQ
What is the max PSI for hookless rims?
72.5 PSI (5 bar) for road rims under ETRTO/ISO. If your rim or tire specifies a lower value, the lower one applies.
Can I mount any tubeless tire on a hookless rim?
No. The tire must be explicitly approved for hookless rims by its manufacturer. Check the rim and tire makers’ compatibility lists.
Can I run inner tubes on hookless rims?
On many rims, yes, as long as the tire is hookless-compatible. The 72 PSI limit still applies, and tubes need slightly more pressure, so a wider tire helps.
How do I know if my rim is hookless?
Hookless rims have straight sidewalls with no hook on the inside. The rim or its spec sheet usually says “hookless”, “TSS” or lists the maximum pressure.
Keep reading
TireDial’s values and the ones on this page are well-founded starting points, not manufacturer specifications. Always stay within your tire and rim limits. See also the safety notice.