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You just pump them up as hard as you can right? It's not quite that simple

Getting the right tyre pressure is simple, right? Pump your tyres to the range recommended on the sidewall and away you go. Turns out it’s not quite that straightforward.

Your tyres do a lot of things. They grip the road so you can steer and go forward. On a road bike, they provide the only significant suspension, cushioning you from bumps and holes. They have to be tough enough not to puncture too easily, but thin and light enough to roll well. All these things are affected by pressure, as well as the design and construction of the tyre itself.

When you sit on a bike, your tyres compress. If they compress too much, they’ll writhe and squirm on the rims, making the bike harder to control, increasing rolling resistance and putting you at risk of pinch punctures. If they doesn’t compress enough, the ride will be harsh and there will be so little rubber on the road that grip will be reduced.

Somewhere in between those extremes, there must be an ideal compromise. How do you find it?

The happy medium

As well as pressure, how much your tyres compress depends on your weight, so if there’s an optimum pressure it will depend on your weight and the type of riding you do.

Engineer Frank Berto, who investigated this issue for Bicycling magazine back in the late 1980s, came up with a formula based on the weight on each tyre; he reckoned that the happy medium involved a tyre being compressed 15 percent of its height.

As a recreational and touring rider, Berto was probably more interested in comfort than speed, so this idea is controversial, because Berto recommends lower tyre pressures than most of us use.

Tyre drop is hard to measure, but Berto did a shedload of measurements, and plotted the pressure needed to give a tyre drop of 15 percent for a range of rider weights and tyre widths. Here’s a graph of his recommendations, showing the relationship between pressure and wheel load for each common road bike tyre size.

bertopresschart-roadcc.gif

Weighty matters

There are two important things to bear in mind here. The first is that the tyre width is measured not claimed. When Berto originally did his work on tyre drop there was a big problem with tyre manufacturers mislabelling their tyres because the easiest way to claim you had the lightest 23mm tyre was to mark a 21mm tyre as a 23mm. That’s improved, but some tyres are still wrongly marked; I recently put calipers on a nominal 28mm tyre that turned out to be just 26mm wide.

The other is that wheel load is per wheel. If you weigh 72kg and your bike weighs 8kg, then your tyres carry a total of 80kg but it’s not evenly distributed. The rear wheel carries more of the load, usually between 55 and 65 percent.

To determine the right pressure, you’ll need to measure the load on each wheel. Put a bathroom scale under one wheel and enough wooden blocks, books or old magazines under the other to level the bike. Lean very lightly against a wall to steady yourself and sit in your normal position on the bike. Get someone else to read the scale for you. Repeat the process with the scale under the other wheel.

If your rear wheel is carrying 44kg and your front 36kg (a 55:45 weight distribution) and you’re running 25mm tyres, then reading from the graph tells you that you want about 90psi in the rear tyre and 70psi in the front.

That’s probably lower than you’re currently running, so think of it as a starting point from which you can tweak the pressure until you get a feel you like.

If the pressure comes out well below the minimum recommended pressure of your tyre, then you can go skinnier; if it’s well above, then use a fatter tyre if your frame will accommodate one.

Controversy

As I mentioned, this approach is controversial. Another engineer, the late Jobst Brandt, author of ‘The Bicycle Wheel’ wrote in a newsgroup posting: “What Berto did not seem to consider is that hard cornering and rough pavement require higher inflation than comfort or other considerations might demand. Banking over to a maximum lateral acceleration of about 1g is not something that works reliably with a comfortably inflated tire, nor is encountering rough pavement with breaks and patches in the surface.”

Brandt was also sceptical about Berto’s notion that front and rear tyre pressures should reflect the loads on them. He wrote: “I run my tires at the upper end of pressure because snake bites are always a threat on mountain roads. When descending with hard braking, the front wheel carries the entire bicycle, with the back wheel at lift-off. The same is true climbing while seated on steep grades where front wheel rise is close at hand.”

More recently, Bicycle Quarterly magazine did some tests that revealed there was no speed advantage in pumping tyres up very hard. It was already known that when measured on a smooth drum rolling resistance didn’t decline much beyond a certain pressure. But as editor Jan Heine discusses here Bicycle Quarterly’s real-world testing indicates that when tyre pressures get too high, there’s no further reduction in rolling resistance. Heine believes that you lose the suspension effect of the tyres and that’s enough to push the rolling resistance back up.

Choices

Where does this leave you and me then? I think there are four take-homes:

If you ride in a leisurely manner — a short commute, gentle pootling around the lanes — then you can afford to run quite low pressures for comfort.

At the other extreme, don’t bother over-inflating your tyres for races and time trials. Unless the road surface is glass-smooth you won’t get any advantage, and let’s face it where are you going to find a road like that in the UK?

In between, you should tailor your tyre pressure to your riding style and roads. Ride in flat country and on smooth roads? Go for the lower end of the range between the Berto 15% drop figure and the range marked on your tyres.

In the hills I’d follow Jobst Brandt’s advice for equal pressures front and rear if you like to descend quickly. I love to go downhill fast (it makes up for the fact you need time-lapse photography to observe me climbing) but a front wheel impact puncture at 50mph is high on my list of things I’m not keen to try, along with BASE jumping and being visited in hospital by David Cameron.

If you're not a demon descender, you can run a softer front tyre for comfort.

For many of these situations, going up in tyre size is also a good idea. Our Mat Brett explored the reasons for fatter tyres in a Trendspotting piece last year. It’s a convincing case.

Gauges

To set your tyre pressure right you’ll need a pressure gauge. Track pumps usually have one built in, but they’re often not very accurate, especially if the pump is a bit old and has been kicked around the workshop floor.

A standalone gauge, properly looked after, is a better alternative. If you can find a sturdy, metal-bodied analogue gauge, grab it but digital gauges like these are more convenient.

Topeak D2 Smart Head Digital Pressure Gauge — £20.89

Topeak digital gauge.jpeg

This well-regarded digital gauge measures in 1psi increments and automatically adapts to Schrader and presta valves. It reads up to 250psi so you can even use it on your mountain bike’s shocks too.

Find a Topeak dealer

SKS Airchecker — £15.96

SKS Airchecker - crop.jpg

Accurate enough for workshop duties, yet compact enought to slip into the smallest of seat packs or jersey pockets, the SKS Air Checker is a very tidy digital tyre pressure gauge.

Read our review of the SKS Airchecker

Find a SKS dealer

Acknowledged by the Telegraph as a leading cycling journalist, John Stevenson has been writing about bikes and cycling for over 30 years since discovering that people were mug enough to pay him for it rather than expecting him to do an honest day's work.

He was heavily involved in the mountain bike boom of the late 1980s as a racer, team manager and race promoter, and that led to writing for Mountain Biking UK magazine shortly after its inception. He got the gig by phoning up the editor and telling him the magazine was rubbish and he could do better. Rather than telling him to get lost, MBUK editor Tym Manley called John’s bluff and the rest is history.

Since then he has worked on MTB Pro magazine and was editor of Maximum Mountain Bike and Australian Mountain Bike magazines, before switching to the web in 2000 to work for CyclingNews.com. Along with road.cc editor Tony Farelly, John was on the launch team for BikeRadar.com and subsequently became editor in chief of Future Publishing’s group of cycling magazines and websites, including Cycling Plus, MBUK, What Mountain Bike and Procycling.

John has also written for Cyclist magazine, edited the BikeMagic website and was founding editor of TotalWomensCycling.com before handing over to someone far more representative of the site's main audience.

He joined road.cc in 2013 and these days he lives in Cambridge where the lack of hills is more than made up for by the headwinds.

59 comments

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TypeVertigo [429 posts] 2 years ago
1 like

At no time have I been subject to the vastly differing effects of tire pressure than with my current set of tires - 32 mm Clement Strada LGGs. Their pressure range is 40-80 psi.

In my experience, they really, really dislike high pressure. They roll very well at 70 psi, but just cannot corner with any real grip, and they are caught out by wet patches very easily. The phenomenon persists down to 65 psi too.

After lots of experimentation I got to my Goldilocks pressures: 45 psi front, 50 psi rear. This was a huge surprise, considering my bike and I weigh around 95 kg. So far, no pinch flats, no squirm, just as much grip as these tires are going to give me.

In contrast, my old set of 28 mm Continental UltraSport IIs were a lot more "straightforward." They were supposedly rated for a 80-105 psi range, so I kept them at 80. There are times when I'd ride tham at 70 or even 65 because of the normal leakage of air through a butyl inner tube, and I didn't come out any worse for wear.

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jackhannaford [25 posts] 2 years ago
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Useful article but the comments exploded! 

 

I just ride my dayum bike  1

 

Also, any chart for a non-pro or non-racing cyclist topping out at less than 90 or 100kg excludes must exclude a large proportion of riders.

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surly_by_name [570 posts] 2 years ago
1 like

"To determine the right pressure, you’ll need to measure the load on each wheel. Put a bathroom scale under one wheel and enough wooden blocks, books or old magazines under the other to level the bike. Lean very lightly against a wall to steady yourself and sit in your normal position on the bike. Get someone else to read the scale for you. Repeat the process with the scale under the other wheel."

Not wishing to throw stones from my glasshouse, but jesus, haven't you all got better things to do (like ride your bike)? On the road, with 25mm tyres, 105-110psi is always the right answer. Except if you are riding tubs, when 125-130psi is probably the right answer. Unless its wet. And your track pump's gauge has a 5-10% margin or error, so there's little point in preternding to be accurate.

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CXR94Di2 [2731 posts] 2 years ago
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I have 3 set of wheels for my bikes, 115kg rider+bike

25mm Tubeless for sportives, comfy and quick  95 psi

40mm tubeless  65 psi comfy for training

25mm tubular 125psi for fast riding

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MariaMartinez [20 posts] 2 years ago
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This topic has been covered in depth on the Fastfitness.tips site, and there is a dynamic tire pressure calculator on there too. Whether it works or not, I don't know. 

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sammutd88 [125 posts] 2 years ago
1 like

I keep it simple. 80-85kg depending on how much ive indulged the past months. 

23c - Don't bother.

25c - 95psi rear/90psi front (tyres are generally 26-27mm mounted: Schwalbe One or Vittoria Corsa G+)

28c - 85psi rear/80psi front

I don't get pinch flats and comfort is great. Can probably drop by 5psi but no point if its working. All the charts I've looked at discriminate that I shouldn't ride a bike at my weight and if I do, my tyres should be at 125-130psi. They're wrong.

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Nick T [1305 posts] 2 years ago
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Very simple formula, easy to remember. Start eith 120  and divide it by two, then add 60, et voila; you're ready to go

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check12 [306 posts] 2 years ago
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Just wrong dude!

i have a tyre pressure gauge also, so I am being accurate.

 

72kg bike and rider 80front 90 rear tyres 26mm measured, nice and comfy, nice and fast  

 

surly_by_name wrote:

"To determine the right pressure, you’ll need to measure the load on each wheel. Put a bathroom scale under one wheel and enough wooden blocks, books or old magazines under the other to level the bike. Lean very lightly against a wall to steady yourself and sit in your normal position on the bike. Get someone else to read the scale for you. Repeat the process with the scale under the other wheel."

Not wishing to throw stones from my glasshouse, but jesus, haven't you all got better things to do (like ride your bike)? On the road, with 25mm tyres, 105-110psi is always the right answer. Except if you are riding tubs, when 125-130psi is probably the right answer. Unless its wet. And your track pump's gauge has a 5-10% margin or error, so there's little point in preternding to be accurate.

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StraelGuy [1746 posts] 2 years ago
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Have to agree with you Check12. I'm 68kg and run 25s at 80psi front and 85psi rear.

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muffies [81 posts] 2 years ago
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im usually lower than these charts on tubeless. 75kg/28mm usually 45psi rear 40 front works well. lower = too lower, higher = less cushiony/a lil slower. maybe i should pump em a lil higher. though the streets here are pretty bad.

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ktache [2136 posts] 2 years ago
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I believe Bike Snob NYC called fred on this regurgitated article .

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Biggus-Dickkus [60 posts] 2 years ago
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Firstly, everyone is assuming tyre gauges are accurate. Well they are not and by a big margin. Before you start setting tyre pressures you must know the gauge you are using is accurate and this should be to 1%, not 3% to 15% as most gauges are. Your average gauge is about 10% out, maybe more. Even Silica (who make £200 to £800 gauges) in their small print say their gauges are 3% accurate. Sorry, but that is just not accurate enough.

In the area of motorsport there are some very accurate gauges available but probably don't go high enough for bicycle tyres.  I wonder what gauges Team Sky use?

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peted76 [1585 posts] 2 years ago
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guyrwood wrote:

Alot of these charts and opinions about sky high pressures is to do with with the traditional mindset that the only good road bike tyre is a rock hard road bike tyre going back to the days of 21 and 23mm tyres.

 

When I hired a bike in Lanzarote recently I took my 25mm Conti Grandprix GT tyres and when the bloke (no spring chicken but amazing at fitting tight tyres with no tools!) went to fit them, he went "Right, what's the max pressure on the side, 120 psi? Right, let's put 120 psi in them". I asked him to put 80 psi in them (I'm 67kg), he wouldn't have a word of it and eventually put 100 psi in as a grudging compromise. Naturally I just let a bit of air out after he'd gone.

 

Witht the popularity of 25+ mm tyres and the increasing evidence about rolling resistance and comfort, the mindset among cyclists will gradually start to change.

In Lanzarote that is normal, the roads are really very good and there's no real need to go lower. 

 

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peted76 [1585 posts] 2 years ago
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Biggus-Dickkus wrote:

Firstly, everyone is assuming tyre gauges are accurate. Well they are not and by a big margin. Before you start setting tyre pressures you must know the gauge you are using is accurate and this should be to 1%, not 3% to 15% as most gauges are. Your average gauge is about 10% out, maybe more. Even Silica (who make £200 to £800 gauges) in their small print say their gauges are 3% accurate. Sorry, but that is just not accurate enough.

In the area of motorsport there are some very accurate gauges available but probably don't go high enough for bicycle tyres.  I wonder what gauges Team Sky use?

I brought a digital tyre pressure reader thingy when I switched to tubeless a couple of years ago, turned out my old track pump was consistantly 28psi under.... 28 PSI !!!! I'd been riding for years on 23mm tyres and tubes at what I thought was 95-110 in actual fact it was 70-80psi!!  

My replacement track pump has been close enough not to think about. 

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Biggus-Dickkus [60 posts] 2 years ago
0 likes
peted76 wrote:
Biggus-Dickkus wrote:

Firstly, everyone is assuming tyre gauges are accurate. Well they are not and by a big margin. Before you start setting tyre pressures you must know the gauge you are using is accurate and this should be to 1%, not 3% to 15% as most gauges are. Your average gauge is about 10% out, maybe more. Even Silica (who make £200 to £800 gauges) in their small print say their gauges are 3% accurate. Sorry, but that is just not accurate enough.

In the area of motorsport there are some very accurate gauges available but probably don't go high enough for bicycle tyres.  I wonder what gauges Team Sky use?

I brought a digital tyre pressure reader thingy when I switched to tubeless a couple of years ago, turned out my old track pump was consistantly 28psi under.... 28 PSI !!!! I'd been riding for years on 23mm tyres and tubes at what I thought was 95-110 in actual fact it was 70-80psi!!  

My replacement track pump has been close enough not to think about. 

 

Yes, but don't be fooled just because the gauge is digital. They are just as inaccurate as the analogue gauges. The problem is that China makes these gauges in millions and they are dirt cheap. The more precise the gauge needs to be the more expensive it costs to make it, plus even when you have a good accurate gauge these should be selected for tight tolerance to about 1%. Probably 1 in 100 would meet the tolerance so the pump/gauge manufacturers don't bother to select the best as it costs too much money. Even Silica quote 3% and that is across the range 0-160psi!!! 

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Thelma Viaduct [82 posts] 1 year ago
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I'm 97kg and run 32mm tubeless at 45psi. Adjust pressure until the ride feels comfortable but not draggy, it's a feel you get, something a calculator won't give you. Sooner be a bit slower and comfortable than a bit faster but aching like f*#k, and not in a sexytime aching way.

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P3t3 [434 posts] 1 year ago
1 like

People actually use guages?

I usually pump my tyres up to a pressure that feels about right by the industry standard " squeeze the tyre" test. Then as the tyres leak over a long time they get more and more comfortable until finally the sidewalls collapse. At this point I pop in a couple of pumps of the track pump so that the rim stays off the pavement. I appreciate this is a little extreme but I don't get pinch flats...

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SKommeren [2 posts] 1 year ago
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I stumbled across a view blog articles from Silca about tyres. In the link below there is the first part 6-7 articles were they go in depth  on a whole scala of things all relating to your tyre (size, pressure, aerodynamics, comfort etc.) It is a mostly chronological, but I though it was fascinating when I read it over a year ago. (you also get some behind the scenes storys when they were working with pro riders riding roubaix etc  1 )

This is not about finding out the perfect tyre pressure for each person or  the ongoing discussion that this can be summarized into one graph or sentence. This is purely for the people how like the sciene behind it! I would highly recommend the read: 

https://silca.cc/blogs/journal/118397252-tire-size-pressure-aero-comfort...

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mathcore [7 posts] 1 year ago
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as a super light rider (I'm 60 kg bike included) with 23 conti gp 4000sII mounted on 31 wide rims  with latex tubes. i can low the presure at 55 psi front 65 rear . more confort , more grip , less rolling resistance . Brussels cobblestones feel like track parquet

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CliveDS [50 posts] 1 year ago
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The charts are not making scense, in every case they have a heavier rider at the max.   I think it's far more about rider experiance and experimenting.   I am 80kg and ride anywhere from 60psi to 90psi on my road bike depending on tire/wheel/comditions.   

 

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mbrads72 [241 posts] 1 year ago
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jackhannaford wrote:

Also, any chart for a non-pro or non-racing cyclist topping out at less than 90 or 100kg excludes must exclude a large proportion of riders.

This chart covers riders up to about 140kg though.

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Plasterer's Radio [551 posts] 11 months ago
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I'm 70kgs and run 25mm @ 70psi & my 28mm @ 60-65psi. Both tubeless.

I am very aware of the comfort advantages of lower pressures when I overinflate to 80+!

They feel like rock and feel like i have less grip at the higher value.

 

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Mungecrundle [1568 posts] 11 months ago
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But pumping them up hard as part of the pre ride psych makes you feel like you should be going faster.

Vittoria Corsa G tubs 25mm, f80 / r110psi, 80Kg all up. Which by pure luck seems to be in the ballpark for the above graphs.

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NickJP [11 posts] 11 months ago
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There is a Berto Tire Pressure phone app in which you enter your weight, the bike weight, wheel and tyre sizes, front and rear loads (if any), and it calculates the F/R inflation pressures to give the 15% drop. I use it as a starting point and usually add an extra few psi to the suggested pressures to get to what seems to work for me.

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antigee [563 posts] 11 months ago
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useful old article resurection - just tidying up and found some tape, valves and sealant hiding out and put them to good use on some 30mm roadish tubeless that I'd intended to set up and never bothered after the struggle to get on with a tube to soften them up a bit  - always been one for pump it up and feels ok but did experiment with the reduce 5 psi and see how goes with my 35mm gravel tyres and was impressed with result - much more comfort 

 just tried the Berto app (cheapskate free trial) suggests 73psi rear and 47psi front - quite a big front rear difference bigger than I'd expect though I'm still getting my head around different pressure front / rear  (took me quite a while to accept different tyres front/rear on mtb) - my guess would have been more like 65 rear 55 front with me weighing in at 72kgs still looks a good starting place

have a digital gauge but really need to buy one that allows you to vent the air as recommended in the article 

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JD84 [6 posts] 11 months ago
1 like

85kg rider + 7kg CAAD10 on 23mm fr 25mm rr Ultrasport 2s @ 100psi. I'm happy.

Ideally I would be 25mm fr 28mm rr @ 85-90psi but too much aero sacrifice on current rim widths.

 

17psi fr 19 psi rear on my 2.8" mountain bike tyres!

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dooderooni [48 posts] 6 months ago
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Regarding the accuracy of pressure gauges, as long as you're only using one then you should be able to get consistent pressures if not totally accurate ones.

I use the MyMavic app to get a ballpark figure then use my Topeak gauge to set the pressure.

As it happens, the 86/89 psi front/rear split that the app suggests is just a little harsh and I drop it down to 80/85. Whether that is a genuine 80/85 psi doesn't matter because it gives me a good combination of grip, comfort, pinch resistance and it rolls well.

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mikeymustard [43 posts] 6 months ago
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I think it's time to update this old article before bumping it up again (very lazy Roadcc, if you cba to update the lame PM joke - David who?? - then at least proofread it), particularly since tyres are getting wider. Also more and more people are hopping on the tubeless bandwagon, which most folks tend to run at considerably lower pressures

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oldmixte [118 posts] 6 months ago
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What is the correct inflation pressure for my tire?

https://www.schwalbe.com/en/luftdruck.html

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