2

enter image description hereJust mounted Mezcal (2.25) and Barzo (2.35) on a i29 rim, tubeless. Then I read the sign on both tyres that says Minimum pressure tubeless 2.00 bar. Ideally I would go for a 1.1 front 1.2 back but I’m freaked out at the perspective of the tyre unfolding in a fast corner.
Any experience running low pressure on these? Why does Vittoria put such a high recommended pressure?

9
  • Isn’t 2 bar like 28psi? That’s really low for 2.25s, wow. Could you attach a pic of the pressure rating markings?
    – MaplePanda
    Sep 11, 2022 at 15:01
  • 1
    Picture added as requested Sep 11, 2022 at 15:53
  • 3
    @MaplePanda: Don’t you mean a lot?
    – Michael
    Sep 11, 2022 at 19:42
  • 2
    Good read here for tire pressure recommendations - enduro-mtb.com/en/what-mtb-tire-pressure. I ride light and precise my early MTB days of the late 80's on fully rigid, and no longer do hardcore -so get away with 2-4PSI below what they suggest. Sidewall recommendations are really lawyer talk for "Don't run to us crying if you burp and crash" - On carbon rims run inserts to protect the rim, aluminum can survive a dents, but best to run inserts if you like really low pressure.
    – mattnz
    Sep 12, 2022 at 1:52
  • 4
    My advice -- start at 2 bar and incrementally air down during a representative ride until things get squirmy.
    – Paul H
    Sep 12, 2022 at 13:43

2 Answers 2

3

The low end of the pressure range noted on MTB tires is usually a very conservative estimate by the manufacturer and not specific to Vittoria (your Rekon/Ardent combination probably also doesn't officially condone such a low pressure). This is even more pronounced with heavy, robust enduro or even downhill casings and lighter riders. Think "better safe than sorry".

Usually, XC tires such as your combination are ridden with a higher pressure than e.g. trail or enduro ones because of the lighter casing. The tire itself is less "stable" so that higher pressures are needed to avoid punctures in rougher terrain. On the other hand, a slightly higher pressure can be ridden with the same level of comfort because the tire casing itself is more flexible.

So my recommendation is to not directly start with 1.2 bar, but e.g. with 1.6 or 1.8 bar and then slowly work your way down until things feel squirmy or you notice the tire hitting the rim. Depending on what you mean by "light enduro" (as noted in the comment), pinch flats would be more of a concern than burping the tire. Burping often only means a loss of air whereas a pinch flat can end your ride!

2
  • My main preoccupation was that of a catastrophic failure of the wheel/tyre structure due to too low a pressure leading to a crash (a downhill turn for example). I feared that applying only half of the minimum recommended pressure could lead to such a risk. From your answers I understand that we can rule out such a disastrous outcome, being the worst case a pinch flat or a "burp". As for the pressure ranges, I remember recently seeing a marking of minimum pressure of 0.8 bars on a friend's Specialized Fast Trak (light XC tyre), so I hope you're reasoning on manufacturer's logic is correct. Sep 15, 2022 at 13:05
  • This catastrophic failure might of course happen. But you can minimize the risk if you slowly drop the pressure over the course of several rides and carefully paying attention to the feel of the ride to identify the warning signs. In my experience, you have to ride turns really aggressively for an otherwise good-feeling tyre to get burping. Rock strikes (-> snakebites) are more difficult to avoid, but again, the same advice applies. Anecdotal evidence: A few weeks back, I thought I might go a little bit lower with my rear pressure. No burping, but the next rock garden killed that tire...
    – anderas
    Sep 15, 2022 at 14:22
0

i'm kind of in the same dilemma. i'm 58kg and using the sram PSI recommendation says i should be using 22-24psi for 650b, 24mm internal at 20 lbs bike, 53mm wide tires, i'd be getting similar tire except the casing would be the durable one and not the the supple casing. wondering if i can get away safely by using pressure between 22-24psi. any suggestions or experience? thank you

1
  • Hi, welcome to bicycles. If you have a question you should ask it instead of posting it as an answer to another question. You might want to take the tour to learn how to use the site effectively.
    – DavidW
    Oct 22, 2022 at 23:59

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.