Minimum MTB tyre pressures?

[Kermit power]

yellowjack said:

Kermit power said:

Do you run your car tyres at 100psi because that's what you have on your road bike?

Eh? You've lost me now....

You're projecting your perfectly sensible road bike paranoia about low pressures onto your MTB tyres, even though they have much tougher construction, and far, far greater air volume inside them.

There's no rational reason to do that any more than there is to feel paranoid about running your car tyres at lower pressure than your roadie tyres. You're only doing it because both are pushbikes, so you instinctively think of them as the same thing.

[yellowjack]

Erm? No, I'm not 'projecting' anything onto anything else. Nor do I fail to notice the many differences between my road and mountain bikes.

Current tyres on the MTB? 26" x 2.0" Maxxis Beavers. Recommended tyre pressure range, as stamped on the sidewall? Minimum 35psi to maximum 65psi. So 45psi would seem be closer to the lower recommended pressure than the maximum recommended pressure.

Nothing to do with my road tyres, nor my car tyres, nor the temperature of my bathwater, FWIW. Just what was recommended by the science and engineering types what designed the tyre. I'm not disputing the fact that many riders seem to have used similar tyres well below these recommended limits, quite succesfully. But I haven't. Oh, and no kittens were harmed as a result of this "over inflation" (?) of my tyres...

[sigh]

...and as soon as the MTB is running again, I'm going to try lower pressures to see whether or not I can teach myself to get along with them.

[anonymous-user]

yellowjack said:

...and as soon as the MTB is running again, I'm going to try lower pressures to see whether or not I can teach myself to get along with them.

Yeah, try it, it was like night and day when I first started alternating between commuting pressures and off road pressures.

I've got a new Mavic wheelset on my Stumpy, off out to give them a spin this afternoon.

[Kermit power]

yellowjack said:

Erm? No, I'm not 'projecting' anything onto anything else. Nor do I fail to notice the many differences between my road and mountain bikes.

Current tyres on the MTB? 26" x 2.0" Maxxis Beavers. Recommended tyre pressure range, as stamped on the sidewall? Minimum 35psi to maximum 65psi. So 45psi would seem be closer to the lower recommended pressure than the maximum recommended pressure.

Nothing to do with my road tyres, nor my car tyres, nor the temperature of my bathwater, FWIW. Just what was recommended by the science and engineering types what designed the tyre. I'm not disputing the fact that many riders seem to have used similar tyres well below these recommended limits, quite succesfully. But I haven't. Oh, and no kittens were harmed as a result of this "over inflation" (?) of my tyres...

[sigh]

...and as soon as the MTB is running again, I'm going to try lower pressures to see whether or not I can teach myself to get along with them.

You were the one who said you'd get paranoid about punctures running normal pressures on your MTB because of your roadie background. I was merely pointing out that the pressure of your road tyres is really no more pertinent to your MTB tyre pressure than it is to your car tyre pressure. Hardly calls for a

I have no idea why MTB tyre manufacturers quote tyre pressures way above the range that anyone would ever use off road, but they do. Maybe they know that the majority of riders won't ever take their MTBs off tarmac?

[Justin S]

I must have the same 'muscular' build as Kermit and run 35 psi on narrow mtb tyres 2 inchers and my Jekyll with 2.3's about 30psi. Nothing less or I feel rims dinking edges and roots. That's with tubeless , as I don't have to worry about snake bites.

[neenaw]

I'm running tubeless on my 29ers and they run around 21psi front and 24psi rear. I'm 75kg.

The road bike has 25c tyres and has 90psi both ends and the Diverge has 30c tyres running 70psi. When I had the CX bike and was doing a few races on it I was running 16psi in mud tyres and tubes at one point and still never punctured or damaged a rim.

[matt-ITR]

yellowjack said:

Good grief!

I don't think I've ever run a MTB tyre below 45psi !!!

On the road, I've chickened out of trying anything below 80psi.

The thinking used to be that harder tyres were faster, but this has been proved wrong off-road and even on roads too.
If you jump from 45psi to 20psi you will hate it, so drop the pressure slowly.

Tubeless is faster as the lack of a tube decreases rolling resistance, but also it means pinch punctures are a thing of the past.

[deadtom]

yellowjack said:

Good grief!

I don't think I've ever run a MTB tyre below 45psi !!!

wow...

Run mine at ~25 psi on both DH bike and hardtail. anything above 30 psi is only if I am riding on the road for any distance

[WestyCarl]

matt-ITR said:

Tubeless is faster as the lack of a tube decreases rolling resistance, but also it means pinch punctures are a thing of the past.

I heard this before but can't understand why the absence of a tube reduces rolling resistance?

[anonymous-user]

WestyCarl said:

matt-ITR said:

Tubeless is faster as the lack of a tube decreases rolling resistance, but also it means pinch punctures are a thing of the past.

I heard this before but can't understand why the absence of a tube reduces rolling resistance?

Because as the tyre and tube deform at the tyre/ground interface, the tube "rubs past" the inside of the tyre as it does so. That tiny amount of energy adds up. (well it does on a road bike, i can't say it will on an MTB where there is so much more drag anyway)

[WestyCarl]

Max_Torque said:

Because as the tyre and tube deform at the tyre/ground interface, the tube "rubs past" the inside of the tyre as it does so. That tiny amount of energy adds up. (well it does on a road bike, i can't say it will on an MTB where there is so much more drag anyway)

So if it "rubs" enough to create noticeable drag why don't the thin tubes wear away.

[yellowjack]

Kermit power said:

You were the one who said you'd get paranoid about punctures running normal pressures on your MTB because of your roadie background. I was merely pointing out that the pressure of your road tyres is really no more pertinent to your MTB tyre pressure than it is to your car tyre pressure. Hardly calls for a

I have no idea why MTB tyre manufacturers quote tyre pressures way above the range that anyone would ever use off road, but they do. Maybe they know that the majority of riders won't ever take their MTBs off tarmac?

Look, your thread and all, and I apologise for derailing it a little.

What I said was...

yellowjack said:

...but as a long time roadie I fear that lower pressures will have me paranoid about riding on flat tyres. I'll spend more time checking for p**ctures than pedaling if I go below 40psi, I swear...

...which was partly tongue-in-cheek, and partly serious. But what I meant was that if I ran lower MTB pressures, I'd be constantly looking down, or stopping to squeeze the tyres, because psychologically they'd feel too soft. Not that I'd suffer an increased number of punctures per mile ridden. So I felt that you'd missed my point, which I thought deserved a sarcastic

Maybe I failed to express myself clearly. If so, it'd be my fault that you misunderstood. In which case, duly withdrawn.

To clarify a number of things, though - 1. I've spent a lifetime taking orders. So when I read "minimum pressure" on a tyre wall, I presume the manufacturer has their reasons for putting it there. Or did, until I realised just how low folk go, and how many folk swear by going low. 2. I don't really consider myself to be either a roadie (not quick enough, don't 'do' fancy coffees, and fail to look suitably stylish outside cafes) or a MTBer (not nearly 'gnarly' enough, complete lack of beanie hats, and too much Lycra™ worn off-road), but simply "a chap who rides bicycles, and always has done". 3. I didn't come on here for a squabble about tyre pressures, nor to recommend my higher pressures to anyone. I just thought it would be a lightener, so that everyone could laugh at the silly old fart and his rock hard tyres. I'm trying to experiment with lower pressures, really I am, but every time I do it just feels like I'm running on a flat tyre and I give up and go back to what I'm used to. Day-to-day that doesn't worry me, but I'd like to get into MTB racing a little more seriously, so to avoid putting myself at a disadvantage I'll probably have to drop my tyre pressures to match those against who I'll be competing.


Sorry again to derail the thread. Hearing what psi's other riders are successful with really has given me the confidence to try lower pressures myself just as soon as I get my MTB fixed, so thank you for starting the thread.

[matt-ITR]

WestyCarl said:

I heard this before but can't understand why the absence of a tube reduces rolling resistance?

It is all to do with tyre deformation.
Loads of info on the net, but one article here.

[GuinnessMK]

louiebaby said:

I run mine at 65psi, and start to notice when they go below about 50psi.

Then again, I only use it for road commuting, so I might not have helped this thread.

(It is fun overtaking people on road bikes though, especially as it hums along nicely, like a small army lorry.)

Nothing further or useful to add.

I do that too!

[PomBstard]

Interesting thread. Intriguing too, as I'd be interested to know the type of terrain people might usually ride - I'm guessing as usual its not one-size-fits-all

I run c.35psi F/R on my FS mtb with 26" wheels shod with 2.1" Maxxis Larsen TT - perhaps a little high, but then I've got a 4-5km ride to get to my local tracks and the tracks themselves are predominantly fairly hardpacked singletrack/firetrail with lots of sharp stones and ledges. I used to ride around 25-30psi but found I was getting lots of pinch flats which has been all but eliminated with higher pressures. Grip is not much of a problem except for some of the sandier parts - top lips of waterbars for example - and these can be easily negated by shifting weight.

[Kermit power]

PomBstard said:

Interesting thread. Intriguing too, as I'd be interested to know the type of terrain people might usually ride - I'm guessing as usual its not one-size-fits-all

I run c.35psi F/R on my FS mtb with 26" wheels shod with 2.1" Maxxis Larsen TT - perhaps a little high, but then I've got a 4-5km ride to get to my local tracks and the tracks themselves are predominantly fairly hardpacked singletrack/firetrail with lots of sharp stones and ledges. I used to ride around 25-30psi but found I was getting lots of pinch flats which has been all but eliminated with higher pressures. Grip is not much of a problem except for some of the sandier parts - top lips of waterbars for example - and these can be easily negated by shifting weight.

I used to run at 35-38psi when I used tubes. Since going to tubeless, I run at 30, and last weekend I dropped to around 28 as it was muddy.

[FD3Si]

All you people saying 'wow, 30PSI is stupid high' - have you ever run tubes? As people have said, tyre pressures on tubed tyres are completely different to tubeless.
Less than 30 PSi on any tyre and tube combo I have ever tried(although I'm a bit of a dinosaur with tech and am running 26s) is snakebite city on anything other than road or super smooth hardpack, and horrible to push into corners.

Edited by FD3Si on Wednesday 2nd December 13:13

[Mr Gearchange]

I run about 26psi for downhill and freeride - if it's really rocky and there are some big square edged hits (like a fast descent of the Llanberis path on Snowdon for example) I'll go to 35psi as I'm not looking for high levels of grip in fast corners but don't want pinch flats.

Places like BPW where there is a real mix I'll use around 30PSI.

All of that said - I'm running dual ply super gravity casing tyres which stand up to pinches very well

[Kermit power]

Just by way of an update on this, I bought myself an SKS pressure gauge. The indicated 30 PSI on my Joe Blow track pump turned out to actually be 22 PSI!!!