# Do bike tires leak air normally?



## FuzeB (Aug 8, 2012)

I pumped the tires on my new bike up to 45 PSI a few weeks ago, and noticed they're both down to 36 PSI now. I tried the water bath test on the front tube and it was fine.

Do tires just leak air naturally, the way balloons leak helium?


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## eb1888 (Jan 27, 2012)

Check the valve too. They can slowly lose pressure. I run trails with 25 pounds in my tires--29x2.25. Otherwise they would be bouncy and lose traction. Smaller diameter or road oriented tires could go with 45psi.


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## SimpleJon (Mar 28, 2011)

They tend to leak a bit over time - I run my road bike at 100psi that needs doing every few days


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## JonathanGennick (Sep 15, 2006)

Tubes do leak over time. I've never paid much attention to how fast mine go down, but nine psi over several weeks is probably not something I'd worry about.


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## Squash (Jul 20, 2003)

FuzeB said:


> I pumped the tires on my new bike up to 45 PSI a few weeks ago, and noticed they're both down to 36 PSI now. I tried the water bath test on the front tube and it was fine.
> 
> Do tires just leak air naturally, the way balloons leak helium?


Yup. That's why checking tire pressure should be one of your pre-ride checks. And the lower your prefered pressure, the more important it becomes.

Good Dirt


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## Gasp4Air (Jun 5, 2009)

All of the above. Even without actual leaks, air will migrate slowly through the rubber, either tubed or tubeless.


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## jeffscott (May 10, 2006)

FuzeB said:


> I pumped the tires on my new bike up to 45 PSI a few weeks ago, and noticed they're both down to 36 PSI now. I tried the water bath test on the front tube and it was fine.
> 
> Do tires just leak air naturally, the way balloons leak helium?


Yes the only question is how fast....if a bathtube test is negative for air bubbles my guess would be about 6 weeks, to go from 45 to 36 with a say 2.25 x 26 tire


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## Guerdonian (Sep 4, 2008)

If you are running tubless they will almost be flat within a month, and lose quite a bit of pressure in a couple weeks.

If you are running tubes, you will lose maybe 10psi a month, and be completely flat over the period of a season, say if you put you bike up for the fall, they will be flat by the spring.

It is always good to check you pressure before every ride, even if that's the old fashion thumb and finger squeeze to make sure its at least close.


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## jeffscott (May 10, 2006)

Guerdonian said:


> If you are running tubless they will almost be flat within a month, and lose quite a bit of pressure in a couple weeks.Not in my experience
> 
> If you are running tubes, you will lose maybe 10psi a month, and be completely flat over the period of a season, say if you put you bike up for the fall, they will be flat by the spring.
> 
> It is always good to check you pressure before every ride, even if that's the old fashion thumb and finger squeeze to make sure its at least close.


I have Maxxis Ignitors on Shimano XTR ust rims.....I sure don't go flat in a month....I do pump up say every 3 weeks.


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## De La Pena (Oct 7, 2008)

^^ Both above are accurate in my experience. True UST 3-4 weeks. Ghetto tubeless every few days. 

Also, drastic temperature swings, like those in the desert southwest where I am (40F in the morning and 100F in the afternoon) play a role in tire pressure.


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## Guerdonian (Sep 4, 2008)

jeffscott said:


> I have Maxxis Ignitors on Shimano XTR ust rims.....I sure don't go flat in a month....I do pump up say every 3 weeks.


Huh, I have Stans and Sun Ringle rims (which also use stan's patent) and they will be down to 15psi or less within a month when not being ridden. Maybe it has to do with the tire casing, I have Kenda Slant 6 on both sets of wheels.


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## jeffscott (May 10, 2006)

Guerdonian said:


> Huh, I have Stans and Sun Ringle rims (which also use stan's patent) and they will be down to 15psi or less within a month when not being ridden. Maybe it has to do with the tire casing, I have Kenda Slant 6 on both sets of wheels.


My Maxxis ignitors are the EXO Protection not the LUST or UST...

I use Stans as well....

Maybe it is the rim seal as well to a degree.


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## AlexDeLarge (Oct 5, 2009)

I have 2 mtn bikes, 1 with Schrader valves, the other with Presta. The former will hold the same pressure for weeks without needing air; the latter loses pressure halfway thru a ride and needs more. These are brand-new tubes with no holes in them. I just really hate Presta valves.


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## Sean831 (May 22, 2011)

schraeder valves tend to lose pressure over time but presta valves are supposed to keep their pressure longer.


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## JaSkynyrd (May 31, 2012)

Guerdonian said:


> If you are running tubless they will almost be flat within a month, and lose quite a bit of pressure in a couple weeks.
> 
> If you are running tubes, you will lose maybe 10psi a month, and be completely flat over the period of a season, say if you put you bike up for the fall, they will be flat by the spring.
> 
> It is always good to check you pressure before every ride, even if that's the old fashion thumb and finger squeeze to make sure its at least close.





jeffscott said:


> I have Maxxis Ignitors on Shimano XTR ust rims.....I sure don't go flat in a month....I do pump up say every 3 weeks.


He didn't say he went flat in a month, he said he lost 10 psi in a month. For me that would be down to 40 psi. Definitely not flat.


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## slumpey (Nov 20, 2011)

AlexDeLarge said:


> I have 2 mtn bikes, 1 with Schrader valves, the other with Presta. The former will hold the same pressure for weeks without needing air; the latter loses pressure halfway thru a ride and needs more. These are brand-new tubes with no holes in them. I just really hate Presta valves.


I have the opposite effect. Presta holds really good, but my Shraeder valve tube needs pumping every 2 days. No leaks.


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## jeffscott (May 10, 2006)

JaSkynyrd said:


> He didn't say he went flat in a month, he said he lost 10 psi in a month. For me that would be down to 40 psi. Definitely not flat.


We were talking tubless not tubed.


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## Harold (Dec 23, 2003)

IME, regular tires with sealant (Conti Mtn King) go flat in a few days.

My UST version of the same tire seems to lose pressure at close to the same rate as a tubed tire, which seems pretty consistent with what the OP is dealing with, and is totally normal.

I have not used any tubeless ready tires to compare. but the casing definitely makes a difference. and also of course the rim seal makes a difference.


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## panajotov (Aug 14, 2012)

They all lose air over time and depending on the weather.


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## De La Pena (Oct 7, 2008)

Sean831 said:


> schraeder valves tend to lose pressure over time but presta valves are supposed to keep their pressure longer.


There is no reason to run presta on a mtn bike. I have always been baffled why people even bother with them. In a race, a presta change just takes more time to change.

Sealant will also seal leaky schraeders if they ever happen to leak.


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## Guerdonian (Sep 4, 2008)

6bobby9 said:


> There is no reason to run presta on a mtn bike. I have always been baffled why people even bother with them. In a race, a presta change just takes more time to change.
> 
> Sealant will also seal leaky schraeders if they ever happen to leak.


I respectfully disagree. Schrader has a few cons that i can think of right away:

1. Larger hole in rim for valve = loss of strength, most high end wheels won't even accommodate schrader
2. Can-not remove valve core to put sealant into tube (though this is also the case with some presta tubes) (EDIT: this is incorrect please see below)

I do like the schrader valves, don't get me wrong, they are great on my cruzer, and much more resilient to hard use when pumping. I do however understand the need for presta.


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## shiggy (Dec 19, 1998)

Guerdonian said:


> Huh, I have Stans and Sun Ringle rims (which also use stan's patent) and they will be down to 15psi or less within a month when not being ridden. Maybe it has to do with the tire casing, I have Kenda Slant 6 on both sets of wheels.


Welcome to the difference between tubeless tires and rims, and tires and rims being used without tubes.

Most of my UST/UST compatible tires and rims will hold pressure for a month or so. A bit better than with an inner tube. I have had one Bonty TLR tire/rim combo hold pressure for 8 months, without sealant.

Using standard tires and/or rims without inner tubes does not make them tubeless any more than riding a road bike on dirt makes it a mountain bike. Either can be done, but there are limitations to the effectiveness and user needs to understand and except the risks.


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## Guerdonian (Sep 4, 2008)

shiggy said:


> Welcome to the difference between tubeless tires and rims, and tires and rims being used without tubes.
> 
> Most of my UST/UST compatible tires and rims will hold pressure for a month or so. A bit better than with an inner tube. I have had one Bonty TLR tire/rim combo hold pressure for 8 months, without sealant.
> 
> Using standard tires and/or rims without inner tubes does not make them tubeless any more than riding a road bike on dirt makes it a mountain bike. Either can be done, but there are limitations to the effectiveness and user needs to understand and except the risks.


Confused here. I have Sun Ringle Black Flag Pro's and also Stans ZTR Crest Wheels (both wheelsets use Stans Tubless rim patent), both wheelsets have Slant Six UST tires, with Stans Sealant. I run between 27 to 32psi when riding based upon trail conditions.

Both wheelsets will lose 5 to 10 psi per week when not being ridden and sitting static in the garage. After a month they are not flat, but they will be low enough pressure to not be ride-able, i would guess 15psi or less.

Edit: thought I had Flows, but I have Crest.


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## shiggy (Dec 19, 1998)

Guerdonian said:


> I respectfully disagree. Schrader has a few cons that i can think of right away:
> 
> 1. Larger hole in rim for valve = loss of strength, most high end wheels won't even accommodate schrader
> 2. Can-not remove valve core to put sealant into tube (though this is also the case with some presta tubes)
> ...


Schrader valve cores are easily removable. The tool comes with most every bottle of Slime and other sealants so you can put in the sealant through the valve stem.

I practice, there is little difference between presta and schrader valves. Comes down to personal preference.

Presta is my choice.


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## Guerdonian (Sep 4, 2008)

shiggy said:


> Schrader valve cores are easily removable. The tool comes with most every bottle of Slime and other sealants so you can put in the sealant through the valve stem.


Didn't know that one. Guess I haven't played with schrader enough. Good to know :thumbsup: Edited my post above.


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## anthonyk (Feb 15, 2012)

Guerdonian said:


> I respectfully disagree. Schrader has a few cons that i can think of right away:
> 
> 1. Larger hole in rim for valve = loss of strength, most high end wheels won't even accommodate schrader
> 2. Can-not remove valve core to put sealant into tube (though this is also the case with some presta tubes) (EDIT: this is incorrect please see below)
> ...


I've found removable cores to be more common on schrader valves than presta, actually. In fact, I don't think I've even seen a schrader valve without a removable core.

Edit: Ha, never mind. :thumbsup:


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## shiggy (Dec 19, 1998)

Guerdonian said:


> Confused here. I have Sun Ringle Black Flag Pro's and also Stans ZTR Crest Wheels (both wheelsets use Stans Tubless rim patent), both wheelsets have Slant Six UST tires, with Stans Sealant. I run between 27 to 32psi when riding based upon trail conditions.
> 
> Both wheelsets will lose 5 to 10 psi per week when not being ridden and sitting static in the garage. After a month they are not flat, but they will be low enough pressure to not be ride-able, i would guess 15psi or less.
> 
> Edit: thought I had Flows, but I have Crest.


Notubes rims are not UST compatible or UST spec. They are a method for conversion, that by their own admission does not work with all tires, and they take no responsibility for failures. Read the disclaimer.

By hold pressure I mean it does not need to be aired up often, not that it has gone completely flat.
Losing 5-10psi per week is not holding pressure, though not too unreasonable.


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## Guerdonian (Sep 4, 2008)

shiggy said:


> Notubes rims are not UST compatible or UST spec. They are a method for conversion, that by their own admission does not work with all tires, and they take no responsibility for failures. Read the disclaimer.
> 
> By hold pressure I mean it does not need to be aired up often, not that it has gone completely flat.
> Losing 5-10psi per week is not holding pressure, though not too unreasonable.


Gatcha, thanks for clarifying, I learned two things in this thread today


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## De La Pena (Oct 7, 2008)

shiggy said:


> Schrader valve cores are easily removable. The tool comes with most every bottle of Slime and other sealants so you can put in the sealant through the valve stem.
> 
> I practice, there is little difference between presta and schrader valves. Comes down to personal preference.
> 
> Presta is my choice.


Touche. Head to head, with a stop watch, I will probably beat you by close to 10 seconds with schraeder tube every time. I only know this because we used to argue with the roady wrenches and end up racing them by changing "flats" when we were bored at the LBS I worked at a few years back.


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## shiggy (Dec 19, 1998)

6bobby9 said:


> Touche. Head to head, with a stop watch, I will probably beat you by close to 10 seconds with schraeder tube every time. I only know this because we used to argue with the roady wrenches and end up racing them by changing "flats" when we were bored at the LBS I worked at a few years back.


Basically the time it takes to open and close a presta valve (the top nut).


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## FuzeB (Aug 8, 2012)

For the record, I just pumped both tires up to 55 psi at 12am on Aug 25th, tire is rated for 40-65 psi. Will check the pressure again in a week.


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## TiGeo (Jul 31, 2008)

Sounds perfectly normal to me. I check my tires every ride.


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## De La Pena (Oct 7, 2008)

Damn thats high. I run 28 in the chunk and 24 in the smooth. Tubeless of course.


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## FuzeB (Aug 8, 2012)

I haven't had a chance to take it on any trails yet, and forget doing any downhill on this cheap BSO. Just riding around the neighborhood for now, mostly plaved, I hear a higher PSI is better for that. First bike I've ever bought myself, legs not in biking shape, etc etc...


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## DavyRay (Apr 13, 2012)

FuzeB said:


> I haven't had a chance to take it on any trails yet, and forget doing any downhill on this cheap BSO. Just riding around the neighborhood for now, mostly plaved, I hear a higher PSI is better for that. First bike I've ever bought myself, legs not in biking shape, etc etc...


Beginners Corner - BSO == bicycle-shaped object.


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## FuzeB (Aug 8, 2012)

FuzeB said:


> For the record, *I just pumped both tires up to 55 psi at 12am on Aug 25th*, tire is rated for 40-65 psi. Will check the pressure again in a week.


It's two weeks later, Friday, Sept 7th 11pm, the bike has been in storage the whole time and both tires are down to 43.7 psi front, 45.0 psi rear. So losing about 0.7 psi/day.

This is either a)normal, b)bad tubes, c)bad tires.


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