I understand that this could be entirely subjective or based on many influencing factors; so I’m going to try and give you some detail and context and hopefully you’ll be able to help me out?

I’m after some suggestion of what tyre pressure I should be running.

I have a 120mm hardtail; I’m not sure of the weight of the bike but it’s honestly not particularly heavy — though no XC whippet either. Approximately 15kg (33lb) — maybe less.

I myself am approximately 65kg. So myself, clothed and laden, plus the bike probably weighs in the region of 85—90kg (187—198lb).

I live and ride in North Wales on intermediate (red) runs. Generally prolonged periods of dry weather are sparse. It’s mostly damp, to be honest.

I would say I was between a beginner and intermediate in terms of my skill level; so no huge jumps but I am happy to try most things like drops and smaller jumps.

I currently have some stock Continental X-King 2.1″ but they are soon to be replaced with Onza Canis 29×2.25″. Apparently as they are retro-skinwall they can squirm at lower pressures when cornering (I read in a review).

So… suggestions on ideal (or at least a starting point) tyre pressure, please?

Given the wide inaccuracy of most pressure gauges, any answer you get here is going to be an approximation of an approximation at best. Seriously, I’d start somewhere that feels about right then add or subtract pressure to suit your preferences. Most likely you’ll need more pressure in the rear tyre than the front. Maybe start with the pressures you currently run and take it from there?

Cheers, BadlyWiredDog.

I understand, but even a starting suggestion would help. Having heard ranges from less than 20psi to over 55psi and the fact I’m going from tubed to tubeless it would be good to have a suggestion or two to start with.

Thanks though!

If you really care get a digital pressure gauge to check pressures more accurately. But around 30psi will set you fine. Go up if you want to roll faster and down if its less rocky and you’re losing grip.

Personally not nothing over 30psi unless it’s really rocky and rim dings are a danger. That is on my pump though, I put the same into one from my mates identical pump and it was way too hard.
I’ve seen people on super soft “for great grip” pressures and then people who stick extra in so they don’t need to worry on the same trail hard to tell who was who until somebody gets a puncture 😉

Start with what you have, let a bit out or put a bit in, learn the feel and hand squeeze as to what feels right and go from there.

17 front 20 rear

ivorhogseye – Member
17 front 20 rear

What gauge?
What tyres?
What Rims?
Tubeless or not?
Terrain?
Style of riding?

numbers on their own are not very useful…

Don’t stans recommend your weight in pounds divided by 7 for tubeless psi?

Then add a couple to the back and take a couple away at the front.

1 have a Trail King on the front at 18psi Racing Ralph on rear at 21psi however the bike is 20lbs, both are 2.25 tubeless.

There are no hard and fast rules, I discovered this when I went tubeless. If I run below 25psi, my tyres squirm on fast corners, which is a sensation I really don’t like. I’m not colossal either, so getting the right pressure is something that takes time and will be season dependent.

If the existing Conti are indeed stock you’ll be able to run decent tyres at any pressure you like and see a marked improvement.

I’m up nearer 90kg + bike and go for 25 to 30 ish in both ends, really this could be 10 – 50 though.

If i can comfortably compress the tyre pushing into it with my thumb they’re too soft but i should be able to squeeze them…

Contact patch will be tyre width squared x pi for two wheels roughly. Weight in lbs (rider and bike) divided by contact patch in inches is what the pressure will be in PSI (pounds per square inch). That’s a good starting point and usually works well enough.
Lower pressure will spread the tyre more making a slightly bigger contact patch therefore better grip but the tyre will squirm. Higher pressure makes the tyre shape more stable but reduces grip.

Twice your weight in stone on the front, a little more on the back.

If it squirms or pinchflats add a couple of psi at a time until it doesn’t. If it feels too bouncy let out a couple of psi until it doesn’t. You can’t get it feeling nicely damped and not boingy without it squirming in berms then you need tyres with stiffer casings and/or wider rims.

@lustyd that works out at just shy of 40psi.

I think I’ll start at 30 and go from there. Maybe even 35psi at the rear and 30psi up front. Then ply around with that.

Cheers!

Yeah you’ll want to be a bit lower usually but it’s a good starting point and guide and works for all tyres including fatties at 4.8″ monsters. The other rules of thumb are only useful for standard tyres and almost nobody rides those now with 29″ plus fat etc 🙂

Sorry maths fail from me! I was being lazy and using full width but that doesn’t work, needs to be half width (radius)
Should have been tyre width in inches /2 then squared then x pi then x2. Divide weight in lbs by this figure. For a 2.1 this works out as just under 7 so in your example of 15kg bike and 65kg rider that’s 176/6.9 = 25.5psi
22psi for the 2.25 tyres

It should feel more like an orange than an apple.

Start at 30 and lower it until you feel it squirm or you hit the rims. Simple.

I generally run at around 30psi but it can differ from tyre to tyre – the Speed King Supersonics on my Epic need to be at 50psi to work properly for example.

Should have been tyre width in inches /2 then squared then x pi then x2. Divide weight in lbs by this figure. For a 2.1 this works out as just under 7 so in your example of 15kg bike and 65kg rider that’s 176/6.9 = 25.5psi
22psi for the 2.25 tyres

weight/(width/2)^2).2pi)=
weight/((width^2)/4).2pi)=
weight/((width^2).pi/2)

For a 12 stone rider:
On 2.3″: 168/((2.3^2).pi/2=20.2psi
On 2.5″ = 17.1psi
On 2.1″ = 24.3psi

Seems a bit on the low side but in the right ball park.

Like Lou Ferigno pinching a slightly over ripe cantaloupe betwixt thumb and forefinger.

Guages are woefully inaccurate. Even the two digital ones i’ve got don’t seem very reliable (i’m wondering if the new one has stans fluid in it already).

I think i run between 20 and 30 but often it’s a thumb test then put as much weight on the front i an as if cornering (ie leaning the bike) when standing next to it and making sure the sidewallls don’t collapse.

what does it say on the tyre sidewall? Inflate to that pressure

I generally start at 25psi in both ends.

Drop the front in the wet or for slower less jumpy / lumpy trails to around 22psi, pump it up to 28 for the rocky fast stuff. I pretty much leave the back at around 25 to 28, only really putting in air when i want a free rolling feel for more XC style stuff.

numbers on their own are not very useful…

That’s exactly what the op asked for. No need for you to comment on my response

My 120mm hardtail is around 11.5kg I’m about 85.
2.2 conti x kings and I run anywhere between 20-30 on the front and 25-40 on the rear depending on what I’m riding, weather, how long the ride is etc. There really is no hard and fast answer I’d start around 25 front 30 rear and go from there.

20psi in Rons/Ralphs 2.25/2.1 here.

what does it say on the tyre sidewall? Inflate to that pressure

With that sort of thinking it would be about 60psi..good luck with that 🙄

doubledunter – Member
With that sort of thinking it would be about 60psi..good luck with that

What tyres are you buying???

Two pumps, about 15 psi difference, so I like to go off feel!

I pump them both up pretty hard, say 35-40.
Harsh and horrible at that stage, so I keep letting a bit out until they become acceptably comfy and grippy.
Make a note of the pressure.

Let a few psi out at a time until the tyre squirms or risks the rims.
Make a note of that.
Then at least I’ve got a working range on a known pump.
Then I just play about within that range til it feels right for me.
Everyone rides their own trails, so it’s really hard to give definite values, tbh

@chiefgrooveguru very clever, but you left off the bike weight which will raise the answer a little. 33lbs for the bike makes a difference!

Total mass is 115 kg. In Les Gets. Conti Barons front and rear, with tubes. DT Swiss XR400 rims. Currently running 30 front, 35 rear on rocky trails in Morzine/ Les Gets. Only one pinch puncture to date, no squirming at all. Tempted to drop the front by a few PSI but narrow rims may lead to a bit of weirdness.

Doesn’t matter where you start: If the pressures are too high, the tyres will ping off everything and lack grip.

As you lower the pressures, the grip will increase.

When you feel the tyres squirm in corners, or you start getting an unacceptable number of rim strikes the pressures are too low.

Experiment a bit an you will find the best pressures for:

YOUR bike,
YOUR rims,
YOUR tyres,
YOUR terrain and
YOUR riding style.

FWIW: I end up with ~17 PSI front and 20 PSI rear on 2.3″ tyres on North Wales XC stuff. A couple of PSI more in the rear on rocky stuff (~85kg total bike+rider).

doubledunter – Member
With that sort of thinking it would be about 60psi..good luck with that

What tyres are you buying???

Minions…check it out

@tillydog the calcs work out to 22psi for your numbers so not far off 🙂