# 25mm tire psi?



## samh (May 5, 2004)

(forgive if this has been discussed). What pressure do you use compared to 23mm tire for your weight? I was using 110-120psi, is this OK? Michelin says I should use 118psi for my weight (23mm).


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## boneman (Nov 26, 2001)

*A bit high*

Most manufacturers spec between 85-100 psi



samh said:


> (forgive if this has been discussed). What pressure do you use compared to 23mm tire for your weight? I was using 110-120psi, is this OK? Michelin says I should use 118psi for my weight (23mm).


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## tarwheel2 (Jul 7, 2005)

It depends a lot on your weight, but I generally lower the air pressure about 5 psi when using 25s compared to 23s. I'm no lightweight and I run about 105 rear and 95 front with my Conti GP 4000 25s.


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## Blue CheeseHead (Jul 14, 2008)

Here is a graph:

http://www.vintagebicyclepress.com/images/TireDrop.pdf


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## Mike T. (Feb 3, 2004)

samh said:


> (forgive if this has been discussed). What pressure do you use compared to 23mm tire for your weight? I was using 110-120psi, is this OK? Michelin says I should use 118psi for my weight (23mm).


90psi is just lovely for my 25mm Michelins. Try different pressures but don't be afraid to go low.


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## boneman (Nov 26, 2001)

*Interesting*

Although I have never, tub or clincher, used pressures anywhere close to the graph. If you read the CONI manual, the Italian Cycling Federation publication from the 70's, the pressures are much lower by .75 to 1.0 bar. Neither is right or wrong, just different although the Berto based graph would put many riders of 65kg+ over the recommended max for clinchers.



Blue CheeseHead said:


> Here is a graph:
> 
> http://www.vintagebicyclepress.com/images/TireDrop.pdf


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## samh (May 5, 2004)

MIke T I got the Open CX 25mm. What pressure?


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## pigpen (Sep 28, 2005)

I run my Open CX 25's at 95-100/105 +/-.
Granted I am 190+.


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## danl1 (Jul 23, 2005)

boneman said:


> Although I have never, tub or clincher, used pressures anywhere close to the graph. If you read the CONI manual, the Italian Cycling Federation publication from the 70's, the pressures are much lower by .75 to 1.0 bar. Neither is right or wrong, just different although the Berto based graph would put many riders of 65kg+ over the recommended max for clinchers.


Mind that the graph is weight per wheel. Figure total weight and weight distribution front/rear, then look at the graph again. Figuring a 65 kg rider, 10 kg of equipment, and 45/55 weight distribution, that's 70ish psi (4.8 bar) front, 90ish psi (6.2bar) rear for 23 tires. 

If anything, that's below recommended minimums rather than over recommended maximums.


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## Rider5200 (Sep 7, 2007)

105 here, front and back. I've experimented with a range of 90-120 and 105 seems to be the best balance between comfort, handling and zero pinch flats (so far...).


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## ewitz (Sep 11, 2002)

Vittoria Corsa EVO CX @ 160 psi


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## MR_GRUMPY (Aug 21, 2002)

PSI is not only determined by weight and tire construction and size, but by road smoothness (pot holes), and if the rider "rides light", or if he "rides heavy".


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## danl1 (Jul 23, 2005)

MR_GRUMPY said:


> PSI is not only determined by weight and tire construction and size, but by road smoothness (pot holes), and if the rider "rides light", or if he "rides heavy".


And in a couple of ways. If the road is very ugly you might need more pressure to prevent pinch flats, though these numbers should protect reasonably if using appropriate widths. But also, if the road is glass-smooth, higher pressures can be faster, since there's less deflection that the tires need to absorb to maintain speed.


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## bwhite_4 (Aug 29, 2006)

I ride my Conti GP4 Season 25's at 100 +/- 2

If I go to 90, my friends keep telling me I have a flat.


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## rsilvers (Nov 27, 2005)

Rider5200 said:


> 105 here, front and back. I've experimented with a range of 90-120 and 105 seems to be the best balance between comfort, handling and zero pinch flats (so far...).


It never makes sense to have the same pressure front and back. Cars often have 50/50 weight distribution, but bikes are more like 40/60. So the front should generally have 2/3 the pressure of the back. If you like 105 in the back, then that would be 70 in the front.


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## Migen21 (Oct 28, 2014)

Pssst. The last post in this thread before yours was almost 7 years ago. Some of the posters on this forum weren't even born then (I presume anyway)


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## bikerjulio (Jan 19, 2010)

Migen21 said:


> Pssst. The last post in this thread before yours was almost 7 years ago. Some of the posters on this forum weren't even born then (I presume anyway)


Even so, it's nice to see a new subject coming up  :Yawn::


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## Kerry Irons (Feb 25, 2002)

bikerjulio said:


> Even so, it's nice to see a new subject coming up  :Yawn::


Let's pin a medal on rsilvers for reviving such an old thread and an old topic. Somebody had to do it.


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## Mike T. (Feb 3, 2004)

Kerry Irons said:


> Let's pin a medal on rsilvers for reviving such an old thread and an old topic. Somebody had to do it.


We just need "shorts or bibs" and "wave or don't wave" resurrected and we'll be all set.


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## Lombard (May 8, 2014)

rsilvers said:


> It never makes sense to have the same pressure front and back. Cars often have 50/50 weight distribution, but bikes are more like 40/60. So the front should generally have 2/3 the pressure of the back. If you like 105 in the back, then that would be 70 in the front.


I concur. I generally run 70 front, 100 rear. Softer in front eases hand fatigue on longer rides. The rear is not only where most of your weight is, but where all of your drive train forces are. Also, pinch flats are rare in the front. Here is a good link below. Be sure to use the 2nd box and enter your TOTAL weight - bike, fully clothed rider, water bottles and anything else you are carrying:

Bicycle tire pressure calculator 

But now I have to break it to you, the price for dredging a thread more than a year old is beers all around for everybody in the thread.


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## fabriciom (Sep 29, 2008)

You don't specify if its tubular or clincher...
I run continental sprinter tubular 25mm at 5 bar.


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