# Tires Max psi is 125. Pump is 115 psi



## dbmcclus (Oct 25, 2005)

I have just purchased a new Trel Pilot 2.1. The tires are Bontrager Race Lite and say max psi is 125. I have an entry level floor pump w/gauge by Blackburn. The specs on the pump say the max air pressure is 115 lbs. Is this enough or do I need to purchase a different floor pump? I have heard that I should run max air pressure in my tires. Also, I am not sure about the accuracy of this gauge. I have presta valve stems and I have heard there is a presta-to-schrader adapter so I can use a standard shirt pocket type gauge that is capable of reading these high pressures. Where can I purchased one of these adapters? My LBS does not carry this adapter. Are these available an an auto supply? Thanks.


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## Cyjal (Sep 9, 2004)

Depending on the size of the tire, your bodyweight and the rims you have on the bike you may not want to go for a full 125.

My Campy rims are rated for no more than 113 with 23s.

I'm certain that someone with practical experience will chime in though.


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## MikeBiker (Mar 9, 2003)

If you want a rough, bouncy, skittish ride, then pump the tires up to 125 PSI. For a good feeling ride that has good handling, pump the tires up to 90 to 110 PSI (depending upon your weight).

The maximum tire pressure is a safety rating that is not to be exceeded (as the tire may blow off the rim). It is not the recommended riding pressure. 

Most shirt pocket type tire gauges do not go high enough to measure bike tire pressures. Unless you know that your pump gauge is inaccurate, trust the gauge. How would you know that the pocket gauge was more accurate?

In general, the higher the tire pressure, the less the comfort level. On thin bike tires the problem with too low a tire pressure is that pinch flats will occur. The heavier the rider, the higher the tire pressure has to be to avoid pinch flats. Larger tires can be run at lower pressures (better comfort) without pinch flatting than smaller tires.


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## dbmcclus (Oct 25, 2005)

Thanks guys for the good advice!

Mike, 
I weigh 150 lbs. What psi do you recommend, maybe 90?


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## TurboTurtle (Feb 4, 2004)

dbmcclus said:


> Thanks guys for the good advice!
> 
> Mike,
> I weigh 150 lbs. What psi do you recommend, maybe 90?


Not Mike, but I would say you would be fine at 90 lbs. I believe the Pilot 2.1 comes with the wider 700 x 25 which will be even harder to pinch flat. I currently weigh 210 and run both 23 and 25 tires at 100 lbs with no problem with pinch flats. - TF


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## geraldatwork (Jul 15, 2005)

dbmcclus said:


> Thanks guys for the good advice!
> 
> Mike,
> I weigh 150 lbs. What psi do you recommend, maybe 90?


I'm not Mike either. It is personal preference,riding style, quality of the roads,etc. I am 210 lbs and run my rear tire at 115 and front at 110. My tires go to 120 lbs I believe. For my "ride" if I was your weight I would probably run the rear at 105 and the front at 100. But again I ride on smooth roads and try to go as fast as I can. YMMV


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## ssif21 (Sep 23, 2005)

dbmcclus said:


> Thanks guys for the good advice!
> 
> Mike,
> I weigh 150 lbs. What psi do you recommend, maybe 90?


I'm STILL not Mike but I second the personal preference point made by the other poster. I weigh 215 and run on Vittorias at 120 and don't find it a bit skittish or bouncy. When these things wear out, I've got Vredesteins to put on which are rated up to 160 psi! I plan on running them about 130.


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## TurboTurtle (Feb 4, 2004)

ssif21 said:


> I'm STILL not Mike but I second the personal preference point made by the other poster. I weigh 215 and run on Vittorias at 120 and don't find it a bit skittish or bouncy. When these things wear out, I've got Vredesteins to put on which are rated up to 160 psi! I plan on running them about 130.


The higher pressure is making you go slower, giving you a harsher ride and decreasing you handling. - TF


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## ssif21 (Sep 23, 2005)

TurboTurtle said:


> The higher pressure is making you go slower, giving you a harsher ride and decreasing you handling. - TF


Huh????? Higher pressure=less resistance=higher speeds. And how would it decrease handling? Since the higher the pressure, the easier it is to turn the tire, it would improve handling.


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## TurboTurtle (Feb 4, 2004)

ssif21 said:


> Huh????? Higher pressure=less resistance=higher speeds. And how would it decrease handling? Since the higher the pressure, the easier it is to turn the tire, it would improve handling.


Wrong. Studies by the tire companies show that for road use the higher pressure increases the rolling resistance and makes it go slower. With a lower pressure the tire casing flexes and soaks up all those little bumps. With high pressure, the entire mass of you and the bike goes up and down. It takes energy to make that mass go up and down and the only energy input comes from you pedaling. Also, all this bouncing up and down means less contact with the road which means less traction and less control.

Any vehicle will go faster with suspension and the major suspension on a road bike is your tires. Liker any suspension, it has to be adjusted to the conditions in which it is used.

TF


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## ssif21 (Sep 23, 2005)

TurboTurtle said:


> Wrong. Studies by the tire companies show that for road use the higher pressure increases the rolling resistance and makes it go slower. With a lower pressure the tire casing flexes and soaks up all those little bumps. With high pressure, the entire mass of you and the bike goes up and down. It takes energy to make that mass go up and down and the only energy input comes from you pedaling. Also, all this bouncing up and down means less contact with the road which means less traction and less control.
> 
> Any vehicle will go faster with suspension and the major suspension on a road bike is your tires. Liker any suspension, it has to be adjusted to the conditions in which it is used.
> 
> TF


Rolling Resistance
"Rolling resistance" is the mechanical friction generated as the tire rolls. As a segment of the tire tread rolls into contact with the road, it deforms from its normal curved shape into a flat shape against the road, then back to the curve as the tire rolls onward. The deformation of the rubber in this process is what causes the friction.
There are two ways to reduce this friction, each subject to trade-offs: 

The thinner and softer the rubber/fabric of the tire are, the more flexible they become. 
The trade-off with this is that the thinner the tire gets, the more fragile it is, and the sooner it will wear out. 

The higher the air pressure, the less the tire will deflect. 
The trade-off with this is that if you pump the tire up too hard, you lose the benefits of pneumatic tires: the ride becomes excessively harsh, and traction will be reduced. In addition, extremely high pressures require a stronger (heavier) fabric and stronger (heavier) rim flanges.

Rolling resistance does decrease theoretically with any increase in pressure, but with modern, high-quality tires the rolling resistance at correct inflation pressure is already so low that the infinitesimal reductions gained are more than outweighed by the trade-offs. 

http://www.sheldonbrown.com/tires.html

____________________________________________________________


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## wim (Feb 28, 2005)

> _Since the higher the pressure, the easier it is to turn the tire, it would improve handling._



If "handling" means high-speed riding, including taking tight curves at speed on less than perfect pavement, excessively high tire pressures will worsen it significantly. The smaller tire contact patch offers less resistance to lateral forces, leading to front-end washout or skittering, and rear wheel hop. Not good for you and those following you if you lose it.


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## MR_GRUMPY (Aug 21, 2002)

If you have 25's, I'd put 90 in front and 95 in back. If you have 23's, I'd put 95 in front and 100 in back. Pretty fair ride and no pinch flats. If you have very good roads and you're the type of person who watches where he puts his front wheel, you could go 90 psi all around, for any size tire.


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## TurboTurtle (Feb 4, 2004)

ssif21 said:


> Rolling Resistance
> "Rolling resistance" is the mechanical friction generated as the tire rolls. As a segment of the tire tread rolls into contact with the road, it deforms from its normal curved shape into a flat shape against the road, then back to the curve as the tire rolls onward. The deformation of the rubber in this process is what causes the friction.
> There are two ways to reduce this friction, each subject to trade-offs:
> 
> ...


Do a search in this forum. You will find lots of discussion and references to the tire company data. - TF


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## TurboTurtle (Feb 4, 2004)

To elaborate (more time today):

First, the esteemed Mr. Brown isn't perfect and a lot of his stuff was written quite a few years ago. It may also be the case of simply a different (limited) definition of "rolling resistance".

Here is a segment from Zipp (http://www.velonews.com/tech/report/articles/7507.0.html)
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The other issue to consider is that most every tire on the market runs at optimal rolling resistance between 105 and 125psi depending on load and road surface condition. We have seen data from numerous manufacturers and had enlightening talks with others to learn that nylon cased tires like Michelin or Continental tend to run optimally around 105-115 and cotton or bias cased tires like Vittoria or Vredestein tend to run optimally at 115-125 maybe as high as 130 for Vredestein, but all of them actually will increase in rr at higher pressures due to the tread rubber beginning to fail in shear as it locally deforms to meet the contour of the road imperfections when the casing is too rigid. Think of it in terms of heat input, as the overinflated tire struggles to conform to all the tiny surface imperfections to make the necessary contact patch, a lot of heat is generated. Not only is there higher rr, but faster tire wear as well at higher pressures, not to mention the tires decreasing ability to stay mounted on the rim as pressure increases. In an ideal world tire manufacturers would list a recommended pressure and not just a MAX pressure (the max pressure is simply a predetermined percentage of the bursting pressure of a given tire as set out by industry standards and has nothing to do with the pressure you should actually run) but they are between the rock and hard place as consumers continually push for higher and higher pressures feeling that ‘if some is good, more is better'. Of course none of this even mentions comfort, which we believe to be of increasing importance as more and more data has shown fatigue to be caused by vibration. It may be that by increasing tire pressure by 20-25 psi, you feel faster as your tires are transfering more of the high frequency vibration to your body (you're feeling a higher frequency 'faster' vibrations' so it really does 'feel' faster) but are actually expending more energy to do it, while simultaneously wearing out the tires faster and inducing fatigue.

Looking to pro road teams, most of them are running 100-110 psi in tubulars and 105-120 psi in clinchers, and this has been a bit of a knock against the clinchers from the pros, that they prefer the lower pressures for improved handling, grip and feel, but need additional air to prevent pinch flats. Especially of issue are rainy races, where they may even lower pressure to 95 psi or so for better grip and control in the corners. The only real exception here would be track racing, especially on wood, where the surface is so smooth that very high tire pressures can yield excellent RR results, but still generally reduce grip slightly, but even this is specific as a board track may runn well at 220psi, but a concrete track favors 150-160psi, and some track surfaces are no better than most roads... For an analogous example, look to Inline Skate racing, where they carefully select the durometer (firmness) of their wheels to the surface they are racing on, this is nearly as critical as ski wax in ski racing as it can win or lose races for you. It is so critical as too hard a wheel will get you dropped like a hot rock on most road surfaces, whereas that same wheel is the only way to be competitive indoors on wood.
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More from Zinn:
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I agree with Josh, and yes, there are lots of test numbers to back it up. It is the same reason a suspension bike (or car) is faster over rough ground - less mass must be accelerated when bumps are encountered, thus saving energy and reducing momentum loss. Every little bump that gets absorbed into your tire (another reason that supple, handmade casings roll faster than stiffer, low-thread-count casings) is a bump that does not lift the entire weight of you and the bike. 

You feel fast on a rock-hard tire for a similar reason that people like the feel of stiff brakes (V-brakes with the levers set on low leverage). The brake feels good and stiff because you are doing more of the work. If you increase the leverage, the brake feels spongy, because the extra mechanical advantage allows a modest pull to squish the pads. 

When you ride a tire at 170psi, the bike feels really lively and fast. That is because you are being bounced all over the place by the surface roughness of the road. However, every time you are bounced, energy you applied to the pedals to get you up to speed is lost. Also, you have less control of the bike, so it feels like it is going faster, even though it isn't. Ever notice how driving down the highway at 75mph in an old Jeep feels crazy fast, and you can cruise smoothly along at 100mph in a nice Saab or BMW and feel like you are going maybe 60mph unless you are looking at stationary objects passing by? 

There is simply no question about it; rolling resistance tests conducted with bicycle tires rolling over surfaces akin to normal road surfaces always indicate the lowest rolling resistance at pressures a lot closer to 100psi than to 170psi! Years ago, for example, I saw results like this at the Continental tire factory. I was told of similar results at a number of other tire factories I have visited. 
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From Michelin:

http://two-wheels.michelin.com/2w/f...codePage=8092004154733_17092004111118&lang=EN

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From Torelli

Don't dynamite your tires. In the last decade it has become an article of faith that the more pressure one puts in a tire, the better (that is, faster) the bike will ride. One brand of tires actually requires 140 psi. This kind of tire pressure makes the bike ride like junk. With super high tire pressures the bike bounces, transmits road shock, fatigues the rider, causes the premature failure of bike frames and components and makes the tires more prone to flats. Running the tires at 105 - 115 psi will yield a bike that corners better and gives a far nicer ride. Try it. It will still go fast.

http://www.torelli.com/tech/tires.shtml
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TF


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## MikeBiker (Mar 9, 2003)

http://www.roadbikerider.com/UArant.htm

* The Case for Lower Tire Pressure* 

_*DEAR UNCLE AL:*_ Perhaps you can settle an argument at our bike club. I like riding 20-mm-wide tires inflated to 120-130 pounds. I feel faster because of what I think is lower rolling resistance. Others argue for a 23C width at 100-110 psi, saying these tires are more efficient because they absorb pavement irregularities better. I weigh 175 pounds and ride at an average of 18+ mph on a variety of road surfaces. So who's right about width and pressure? -- Greg C.

 *UNCLE AL FIRES BACK:  *Soften up, Greg!

Most everyone I know runs too much pressure. Welcome to the club. Over many years of testing and talking to guys who live on their bikes, I'm convinced there is little reason to run more than 95-100 psi -- and there are compelling reasons to run 85-90 psi.

High pressure, say 100-120 psi, guarantees short tire life, poor cornering and lots of punctures. A rock-solid tire cuts/punctures more easily than it would at a lower pressure. Also, a softer tire can "smear" -- conform better to objects encountered on the road. Why make the ride even rougher on America's ever-crumbling road surfaces?

Admittedly, I weigh 210 pounds and ride on really poor road surfaces. These things influence my opinions. I run 85-90 psi front and 90-95 psi rear on 700x23C clincher tires. _I do not have flats! _ Plus, bumps are less of an issue, and my bike corners as if on rails on high-speed descents. I get 1,000-1,500 miles out of a rear tire. When I ran much higher pressure many years ago, I got no more than 500 miles.

So, my advice is never to run smaller than 23C. Use good tubes, air them up before every ride and spend extra for premium tires -- they'll pay you back in extra mileage and better handling.

One more thing: _Don't_ buy a race-specific tire to train on. If it's advertised to last only 500 miles, they aren't lying. Shaving grams off of training tires is silly and wasteful, and you won't get the low-weight advantage when event time comes if you ride the light stuff all the time. Make gram shaving your secret weapon, if only in your mind, when it counts.

Do as I recommend and I promise fewer flats, happier miles and no noticeable increase in rolling resistance (the great myth). Plus, you'll waste fewer resources, both financial and natural.


*FEEDBACK FROM ARNIE L.: *As a roadie of 20+ years, but a new reader of _RoadBikeRider_, I was intrigued (and skeptical) of your advice to lower tire pressure. I have been riding at 125 psi or more, concerned about rolling resistance (although the extra 10 pounds around my waist probably matters a _whole_ lot more to my performance). 

Well, I thought I'd try it. I lowered my pressure to 105 psi. What a great difference! I haven't really noticed any change in performance, but what a difference in the ride! One of my usual rides over badly cracked roads (usual Pennsylvania stuff) was _sooo_ much more comfortable. It seemed like the road had been repaved. Thanks for the advice.


_*FEEDBACK FROM MICHAEL A.: * _Recently, a friend told me about your promotion of lower tire pressure. _GREAT!_

In the early 1960s, I rode the _kermesses_ around Antwerp for a team sponsored by "Cycles OK." We always rode tubulars at about 90 psi with great results -- fewer flats and better handling, especially in the rain (a frequent occurrence in Flanders).

I've tried to promote lower pressure as a coach with the New York Cycle Club, with little success. My fellow club members see my gray hair and my inability to keep up with the hormonally besot, and reject my advice. It's great that you're putting out this sound advice.


_*FEEDBACK FROM SAL A.: * _I've been riding for years with high pressures in my 23C tires (120-130 psi rear, 100-110 psi front). I figured since I weigh around 215 pounds I need this.

I was pleasantly surprised to find out how much better my bike rides after lowering the pressures as Uncle Al recommends.

I rode over some freshly "chipped" roads on my latest ride. This is where the road is covered with hot tar and then pea stone is spread on top. It makes for pretty anxious riding, especially down hills. I was really happy with the improvement in handling.

Also, on smooth asphalt the tires now “sing” lightly. They never did that before! I like the sound and it seems to confirm that I'm riding with the right tire pressure.

I love when I learn something new about bicycling, especially when it's simple and effective. My helmet's off to Uncle Al.


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## lawrence (May 17, 2005)

Very interested read on lower pressures but now what pressures should I be running as I'm heavier than most. I'd like to start running lower air pressures but I don't want to go to low for my wait. My air compressor will blow up to about 90 and then I'd have to put the pump on to go higher.
I'm 230 lbs and have 700x23. Maybe 100 in front & 105 in back? Or can I go lower?


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## omniviper (Sep 18, 2004)

wow glad i read this forum. im only 135 lbs and ive been running 125's on all my tires. Yes i do feel fast but its probably psychological. what should be my target psi? 100?


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## Blue Sugar (Jun 14, 2005)

Does the tire have a recommended pressure printed on the sidewall, in addition to the max? Most do. I find that tires ride best at recemmended pressire, which is usually about 110 psi. I weigh about 160-165 and i find that 110 works best. Don't asume that less pressure will give a better ride.


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## MikeBiker (Mar 9, 2003)

I'm 175 pounds and I use 100 PSI in the front 23c and 100 PSI in the back 25C. I have never pinch flatted at those pressures. I could probably drop both down to 90 PSI with no problems. I don't check pressures everyday and it is not unusual to check after a ride and find that they were in the upper 80 PSI's without giving me a problem. I seemed to flat more when I ran higher pressures.


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## S2H (Jul 10, 2005)

TurboTurtle said:


> In an ideal world tire manufacturers would list a recommended pressure and not just a MAX pressure.


What about my Vittoria Open Corsa Evo CX tires? The tire says 8-10 bar. Does this mean I should not run a pressure below 8 bar? I seem to be wearing my rear tire very quickly at 120 psi...


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## Kerry Irons (Feb 25, 2002)

*Ignore the minimum*



Scotty2Hotty said:


> What about my Vittoria Open Corsa Evo CX tires? The tire says 8-10 bar. Does this mean I should not run a pressure below 8 bar? I seem to be wearing my rear tire very quickly at 120 psi...


This rating on the tire is really the "range of maximums" (under different conditions), not the minimum and the maximum. You can run at any pressure below the max as long as you don't pinch flat. Lower pressure will give you more rubber in contact with the road, and therefore a wider "wear zone" on the tread. This could likely result in longer tire mileage before the tread casing starts to show through.


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## S2H (Jul 10, 2005)

Kerry Irons said:


> This rating on the tire is really the "range of maximums" (under different conditions), not the minimum and the maximum. You can run at any pressure below the max as long as you don't pinch flat. Lower pressure will give you more rubber in contact with the road, and therefore a wider "wear zone" on the tread. This could likely result in longer tire mileage before the tread casing starts to show through.


That's what I figured... But how do I know at what pressure I will pinch tubes at? I'm 185 lb, so I figured I probably shouldn't ride at less than 100. Is that about right? Or does it all depend on my rims?


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## Guest (Nov 28, 2005)

Unless you are riding on a track there is no reason to ever run your tires higher than 100 - 105 PSI.

This will improve the ride, decrease resistance and make your tires last longer.

One of the funniest things I saw this year was watching a bunch of the young hot-shots getting ready for a local time trial and pumping their tires up to 130 - 140 PSI before heading out.

Utter nonsense, keep ' em at 100 and watch your riding improve.


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## geraldatwork (Jul 15, 2005)

Due to this and other posts on other forums I'm slowly reducing the pressure in my tires. (700X23). I used to ride 115-20 in the rear and 110 in the front. I've slowly comming down to a little over 110 in the rear and 105 in the front. I'll settle around there or slightly lower as I am 210 lbs and ride on smooth roads.


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## Kerry Irons (Feb 25, 2002)

*Lower limit for pinch*



Scotty2Hotty said:


> That's what I figured... But how do I know at what pressure I will pinch tubes at? I'm 185 lb, so I figured I probably shouldn't ride at less than 100. Is that about right? Or does it all depend on my rims?


It mostly depends on your weight, your local road conditions, and your riding style. Some people sit dead on the saddle and make little effort to dodge road problems. They will need higher pressures than those who watch where they're going and rise out of the saddle a bit when when they can't avoid a hit. At your weight, 100-110 psi should be fine (the accuracy of most gauges is no better than this).


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