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!
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).
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.
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).
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.