Going lower than the minimum recommended tyre / tire pressure on tubeless

Hi All

I moved to tubeless tyres last year but have kept to the minimum recommended psi on the tyre (85 or 90 psi depending on the tyre). However, this is higher than the pressures I ran when using tubes (75 / 85 psi) which seems to defeat one of the benefits of running tubeless in the first place!

Is it OK to go lower than the minimum recommended pressure printed on the tyre. Is this just an example of manufacturer CYA or is it important not to go below the minimum recommended pressure for safety reasons?

For info, I’m 72 - 73 kg and run Bontrager R3 tubeless on Bontrager Paradigm Elite wheels (19.5 mm inner rim). I’m thinking I should be running pressures more like 75 psi rather than the minimum recommended 90!

What’s the view of the TR community?

I’ve never seen a minimum pressure, only max and suggested. I think they quote that to prevent potential sidewall damage from rim strikes, tube snakebite flats, rim damage, control for rims they don’t make, and legal ass covering. If you’re tubeless, you can run 30psi can get away with it on a smooth road. If you’re on 28 or 32, you’d probably want to be 65-75psi without question.

That tire is made in the same factory as Vittoria with different combos of the same stuff. They have min pressure also. I think this because they have some “open tubluar” (thin sidewall tires).

Edit: https://cyclingtips.com/2018/09/understanding-bicycle-tyre-standards-and-pressure-recommendations/ ETRTO and ISO 5775 spell out minimum tyre pressures - this is in place to give tire producers guidelines and legal cover.

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I’m a bit lighter (circa 60kg) but Ive been running tubeless for several year now and will pump them up to circa 85psi and use them for several weeks with no perceivable loss of performance, arguably more. When I next top them up they’ve often fallen to 40-60psi. (Edit I’ve actually seen 20psi a few times and its been fine) Its perfectly OK IME to go below there’s no tube to get pinched from the pressures being too low and its far comfy and confidence inspiring as they deform to provide a larger contact area and grip the surface instead of bouncing off it.

  • Min / Max listed on the tire wall is quite common.

In this case, Trek lists it on the web for sure, and on the tire AFAIK (still looking for a pic since I am not within reach of my bike).

Notably interesting in the spec above, there is no minimum listed for the 32 version. No idea why.

I had made a few revisions and saw that… basically the answer is ETRTO standard says the min pressure is 30% deflection with a given load. I doubt they tested every single tire., so they are going with the one they tested and C&P’d. We can deduce they tested a tire that came in 28c max and had a soft sidewall given the high min and low max.

Looking at the specs (170tpi), these are made by Maxxis (or the same factory) and probably maps to this tire High Road | Maxxis Tires USA which doesn’t list a min pressure.

I run tubeless for CX and MTB, so I realize this isn’t exactly an apples to apples comparison, but I never get near the min listed pressure. I’ve got a race tire here with a minimum listed pressure of 35psi. For a race I’ll usually go somewhere in the 20-22 psi range (I’m 72kg).

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Thanks for the replies, Guys.

Sounds like I’m being conservative in sticking to the minimum recommended pressure so will gradually start lowering in small increments to see how it feels.

Also interested in whether people run slightly higher pressure in the rear tyre due to more weight distribution on the rear or do you just run tyre pressure equally ?

I don’t really worry about the exact psi. I just pump them both up to circa 80-85psi and leave for a few weeks before having to pump them up again.

That table makes no sense. You would expect there to be a decrease as you move from 25 to 28, and again from 28 to 32. Looks like they just cut and pasted from 25mm.

@Sundance

The big difference between the apples to oranges here, is that a CX wreck in a rocky off-road off camber has a way lower litigation (injury) risk than descending a canyon paved road with a Chevy Suburban trailing you into every corner…

I also ran my CX tires below recommended minimum for off-road training and racing (back when I used to do that), but being close to 88kg, usually pretty close to the minimum. I actually try to rail some corners to make sure they don’t burp under my high G turns.

Pirelli Cinturato 26c

  • tube pressure 87-116psi
  • tubeless 72-87psi

Came with a chart:

The Conti 5000 TL have a warning to only use on hooked rim, a max psi and no minimum pressure.

My Enve (hooked) rims have recommended pressures and a max to prevent the tire bead from blowing off the rim.