Tyre pressures.

Having never had a (bike) tyre pressure gauge in my life, I now have a wonder thing floor pump that has a gauge. I’ve always pumped up my (mtb) tyres until they are nearly hard, with just a bit of give in them.
Changing tyres yesterday, on the side of the tyre was ‘recommended 40psi, Max. 60psi’. OK, I’ll use the new pump and see.
I got to 40 psi, and the tyres are rock hard, I mean, no flex at all in them. Far harder than I’d ever do with with a conventional hand pump. With the max at 60psi, how do you get that high, and why would you?
The 40psi seems rather too hard for me, but is that because the FS suspension takes care of the bumps, rather than the tyres on rigid bikes?
And do people still just feel the tyre, a bit of flex in it, thats good?

What kind of tyres and what kind of riding are you doing? 60psi is a maximum not a target, unless you’re pootling along canal paths in which case it might be perfect.

I’ll start with an assumption that you are running A) tubeless, and B) reasonably sized modern tyres, 2.3ish.

That out the way… FORTY psi!?

Start at Twenty!

I’m Mr Average at 5ft10, 78kg on a middle travel trail bike with 2.3 or 2.4 tyres Exo casing tyres and I start with 19 front, 21 Psi rear.

(The writing on the side of the tyres is what the casing can safely take without exploding – its not in any way relevant to the pressures you would typically run)

Depends on numerous factors but 40psi is too hard for off-road generally. Even on the road some of the evidence would have you lower than that for rolling resistance. Normal weight rider on chunky tyres in proper terrain, I’d be closer to 20. Smooth gravel tracks I’ll have between 35 and 40. There was a time I’d pump to 60 for the latter but the science no longer seems to support it.

i have 80psi in the pump track bike for ultimate rolling, 40psi in the gravel bike for good rolling, and 27psi front and 32psi rear on the trail bike. 110kgs in kit.

The tyre deforming aids with grip, too low and it flops around and offers no support.

It’ll depend on your weight, type of trail, and tyre size, but for off-road, generally 20 to 30 psi front, 25 to 40 rear. Unless you are extremely heavy, there’s no reason to go over 40 psi with MTB tyres.

‘recommended 40psi, Max. 60psi’

That’s from ETRTO, a legal arse covering exercise.

I don’t think i’ve achieved the recommended pressure on an MTB tyre since the late 90’s when we used to race hard and fast for flat/smooth courses and deal with the loose teeth on the drive home…

I’d start by pumping it up to your normal pressure based on feel, and then take a look at the gauge to see what it is.

The right pressure for you is just personal preference, up to a point. Also based on your total riding weight, riding style, trail composition and conditions, type of bike, tyre size, tubes or tubeless, etc etc…

Somewhere between 20 and 30 psi is probably normal for mtb. FWIW I run roughly somewhere between 20 & 25 (harder at the back, softer at the front) on my hardtail with 2.4 tubeless tyres. My road bike is pumped up to 90, once it gets  below 80 or so it starts feeling a little squishy for my taste.

(The writing on the side of the tyres is what the casing can safely take without exploding – its not in any way relevant to the pressures you would typically run)

+1

Edit: oh, and re this:

And do people still just feel the tyre, a bit of flex in it, thats good?

Yes absolutely. I tend to go with the gauge now I’ve got one, but plenty of people don’t bother. If it feels good, it’s good. A gauge is mainly just a way of staying consistent, or a reference point to know by how much you are adjusting it by if you choose to try harder/softer.

If running tubes you’ll be just under 30 PSI maximum.  Even my CX bike only runs 40 max on the 38c tyres. I only run 30 in the fully rigid MTB.

Schwalbe has an online pressure calculator if you want a quasi-objective start point, but pressure gauges can vary a fair bit as do personal preferences, riding styles, terrain etc. I run 22 front, 24 rear mostly on 2.4″ tyres on my pump gauge, but god knows what it actually is. Lower than 40psi though…

https://www.schwalbe.com/pressureprof/

Silca also has an online calculator, but more skewed to road/gravel.

https://silca.cc/pages/pro-tire-pressure-calculator

Again, a starting point for experiment rather than a rule. If they feel too hard, lose a couple of psi and see what happens, too soft, add a couple. Trust how the bike feels to you.

Im 100kgs

on gravel I run 35psi rear, 33psi front as per the zipp calculator recommendation

on trail bike with exo plus maxxis, circa 22psi rear, 20psi front.

on the enduro bike with DD maxxis, again, circa 22psi rear & 20psi front.

if rocky or racing ill go up 1 or 2 psi on tbs, if very wet & muddy, down 1 or 2 psi on the gravel.

just putting that out there for balance.

Do yourself a favour and get a separate gauge for more accurately checking pressures – something like the Topeak D2. Yes, if you’re always using the same pump to inflate tyres then you’ve got consistency, but most track pump gauages won’t have a usable indicator.

Similar to others and for reference, I’m 90kgs, my pressures are (all tubeless):

Gravel 700×50: 35psi front, 38psi rear

MTBs: generally 19-20psi front, 23-24psi rear on Maxxis EXO casings, 2.3-2.5″

but most track pump gauages won’t have a usable indicator.

Some pumps use the same thread as a 63mm commercial gauge. Which don’t cost much at all. And some even come with calibration certs.

And do people still just feel the tyre, a bit of flex in it, thats good?

very much so, I honestly don’t have the first clue what PSI any of my tyres are. Not dead yet.

20psi on the rear

18psi on the front

This is for my mountain bike, with continental Kryptotal and xynotal tyres, enduro casing.

2.3/4 ish tubeless 29er tyres. I’m 105kgs and usually gor for about 25psi rear, and a bit less on the front. My Joe blow 2 is about 3 psi out from my lifeline digital pressure gauge.

All relative though, as someone said start around 20 and see what it feels like.

Around double your weight in stone (on tubeless MTB tyres) remains a good starting point. I run a bit less because of inserts and a lack of very spiky rocks around here.

I’m currently 100kg and hate ‘squirmy’ tyres when cornering hard and I only run 30psi, which most people think is too hard. Although the jump/pumptrack bike is running 50-60psi

Most XC riders were running under 20 psi at the recent world cup round, and that’s in relatively small and supple XC tyres

https://www.pinkbike.com/news/tire-set-ups-of-world-cup-xc-riders-from-val-di-sole.html

Mostly small and supple riders too.

(though my 1990s racing brain thinks that 2.4″ is massive for an XC race tyre, 1.9″ is where it’s at!)

Not a member of the cult of tubeless and detest squirmy tyres. Typically 50psi up front and 35-40 out back. 50psi both ends on the full susser.

That sounds nuts alz. I’m sure there’s some combination of tyre casing, pressure, and possibly tyre insert that would give you much better grip and comfort without any squirming. Please try it if you haven’t, wouldn’t want you to be missing out!

20psi is a good base point for most riders 70-90kgs on mtb with 2.3-2.6, tubeless tyres. I’m a bit lazy so settle for anything 18-22 rear and 16-20 front. That’ll do.

Steeper and loamier riding generally means you’re going to favour grip over low rolling resistance.

Higher speed, bigger jumps and more rocks will tend to require more pressure, to stop rim dings or tyres rolling off bead seats.

Full fat ebikes, being a bit heavier, you’ll tend to want a psi or so more than a meat-powered bike.

If you just ride fire roads and tow paths (which is fine – each to their own) then yeah, 30psi perhaps.

Your weight is important too. Im light so run lower pressures than a heavier rider. As low as 11psi in a 2.6 29er. 28psi in a 38c gravel tyre.

40psi on an mtb is crazy.