Proper Tire Inflation

[Roger Zoul]

I've read a bit on this on Sheldon Brown's site, however, I'm looking for a
more precise answer, if possible.

My road bike tires say that max inflation is 130 psi. Okay, before my last
25 mile ride, I inflated my front tire to 130 psi, since I wanted to roll
easy. So I do the ride okay, get the home & put the bike up w/ no problems.
Next time I go for it, the front tire is flat. Get the tube off to find it
split several inches along the inside seem, so it appears to me that this
was due to over inflation. Was it? And if so, could I have avoided this by
inflating to 125 psi, instead of 130 psi? It was a clear & sunny day, so
there was no need to have less air in the tire. How close to max can one
go, in general? Maybe a had a slightly bumb tube?

Thanks.

[Dan Brussee]

On Mon, 8 Dec 2003 15:00:18 -0500, "Roger Zoul"
> wrote:

>I've read a bit on this on Sheldon Brown's site, however, I'm looking for a
>more precise answer, if possible.
>
>My road bike tires say that max inflation is 130 psi. Okay, before my last
>25 mile ride, I inflated my front tire to 130 psi, since I wanted to roll
>easy. So I do the ride okay, get the home & put the bike up w/ no problems.
>Next time I go for it, the front tire is flat. Get the tube off to find it
>split several inches along the inside seem, so it appears to me that this
>was due to over inflation. Was it? And if so, could I have avoided this by
>inflating to 125 psi, instead of 130 psi? It was a clear & sunny day, so
>there was no need to have less air in the tire. How close to max can one
>go, in general? Maybe a had a slightly bumb tube?

Your answer is in your own text. The tire's max inflation is 130, and
it survived the 130psi just fine. The tube, however did not fare so
well. Sounds like you had a bad tube. It is interesting though that
you say it was "split several inches along the inside seem". Is that a
several inch long split, or in several inches from the valve, or
something else? A several inch split would tell me it blew while
inside - after the ride. Otherwise, you would have been riding on the
rim.

[Roger Zoul]

Dan Brussee wrote:
:: On Mon, 8 Dec 2003 15:00:18 -0500, "Roger Zoul"
:: > wrote:
::
::: I've read a bit on this on Sheldon Brown's site, however, I'm
::: looking for a more precise answer, if possible.
:::
::: My road bike tires say that max inflation is 130 psi. Okay, before
::: my last 25 mile ride, I inflated my front tire to 130 psi, since I
::: wanted to roll easy. So I do the ride okay, get the home & put the
::: bike up w/ no problems. Next time I go for it, the front tire is
::: flat. Get the tube off to find it split several inches along the
::: inside seem, so it appears to me that this was due to over
::: inflation. Was it? And if so, could I have avoided this by
::: inflating to 125 psi, instead of 130 psi? It was a clear & sunny
::: day, so there was no need to have less air in the tire. How close
::: to max can one go, in general? Maybe a had a slightly bumb tube?
::
:: Your answer is in your own text. The tire's max inflation is 130, and
:: it survived the 130psi just fine. The tube, however did not fare so
:: well. Sounds like you had a bad tube. It is interesting though that
:: you say it was "split several inches along the inside seem". Is that
:: a several inch long split, or in several inches from the valve, or
:: something else? A several inch split would tell me it blew while
:: inside - after the ride. Otherwise, you would have been riding on the
:: rim.

Thanks. The tube had a split along the inside seem that was several inches
long. I would not expect a puncture to produce a split like that, on the
inner radius of the tube. Also, I don't think I was riding on the rim --
that I have learned to notice :)

[psycholist]

"Roger Zoul" > wrote in message
...
> I've read a bit on this on Sheldon Brown's site, however, I'm looking for
a
> more precise answer, if possible.
>
> My road bike tires say that max inflation is 130 psi. Okay, before my
last
> 25 mile ride, I inflated my front tire to 130 psi, since I wanted to roll
> easy. So I do the ride okay, get the home & put the bike up w/ no
problems.
> Next time I go for it, the front tire is flat. Get the tube off to find
it
> split several inches along the inside seem, so it appears to me that this
> was due to over inflation. Was it? And if so, could I have avoided this by
> inflating to 125 psi, instead of 130 psi? It was a clear & sunny day, so
> there was no need to have less air in the tire. How close to max can one
> go, in general? Maybe a had a slightly bumb tube?
>
> Thanks.
>

It's quite common for people to pump their tires right to the max psi or
even slightly beyond. I don't recommend going beyond, but I know it's
pretty commonly done by folks like triathletes and that who believe they're
reducing rolling resistance.

Sounds to me like you had a bumb tube, but I'd make sure your rim tape is
covering all the spoke holes on the rim and that there aren't any exposed
edges that could create a hole.

One last thing. High psi isn't good for all wheels. Some of the fancy,
low-spoke count, light weight wheels can develop cracks at the spoke holes
if you keep the tire pressure too high.

Bob C.

[[email protected]]

Roger Zoul writes:

> I've read a bit on this on Sheldon Brown's site, however, I'm
> looking for a more precise answer, if possible.

> My road bike tires say that max inflation is 130 psi. Okay, before
> my last 25 mile ride, I inflated my front tire to 130 psi, since I
> wanted to roll easy. So I do the ride okay, get the home & put the
> bike up w/ no problems. Next time I go for it, the front tire is
> flat. Get the tube off to find it split several inches along the
> inside seem, so it appears to me that this was due to over
> inflation. Was it? And if so, could I have avoided this by
> inflating to 125 psi, instead of 130 psi? It was a clear & sunny
> day, so there was no need to have less air in the tire. How close
> to max can one go, in general? Maybe a had a slightly bum tube?

Tubes cannot split open in the tire from high pressure. Your tire
blew off the rim while you weren't there or you would have heard it.
You should probably run tires at 120psi or less, and don't expect to
descend steep braking hills at that pressure either.

http://draco.acs.uci.edu/rbfaq/FAQ/8b.4.html

This is not new.

Jobst Brandt

[David Kerber]

In article >, says...
>
> "Roger Zoul" > wrote in message
> ...
> > I've read a bit on this on Sheldon Brown's site, however, I'm looking for
> a
> > more precise answer, if possible.
> >
> > My road bike tires say that max inflation is 130 psi. Okay, before my
> last
> > 25 mile ride, I inflated my front tire to 130 psi, since I wanted to roll
> > easy. So I do the ride okay, get the home & put the bike up w/ no
> problems.
> > Next time I go for it, the front tire is flat. Get the tube off to find
> it
> > split several inches along the inside seem, so it appears to me that this
> > was due to over inflation. Was it? And if so, could I have avoided this by
> > inflating to 125 psi, instead of 130 psi? It was a clear & sunny day, so
> > there was no need to have less air in the tire. How close to max can one
> > go, in general? Maybe a had a slightly bumb tube?
> >
> > Thanks.
> >
>
> It's quite common for people to pump their tires right to the max psi or
> even slightly beyond. I don't recommend going beyond, but I know it's
> pretty commonly done by folks like triathletes and that who believe they're
> reducing rolling resistance.
>
> Sounds to me like you had a bumb tube, but I'd make sure your rim tape is
> covering all the spoke holes on the rim and that there aren't any exposed
> edges that could create a hole.
>
> One last thing. High psi isn't good for all wheels. Some of the fancy,
> low-spoke count, light weight wheels can develop cracks at the spoke holes
> if you keep the tire pressure too high.

How does that happen? I can see cracking from too-high spoke tension,
but not from too-high tire pressure.

--
Dave Kerber
Fight spam: remove the ns_ from the return address before replying!

REAL programmers write self-modifying code.

[Chris Neary]

>> One last thing. High psi isn't good for all wheels. Some of the fancy,
>> low-spoke count, light weight wheels can develop cracks at the spoke holes
>> if you keep the tire pressure too high.
>
>How does that happen? I can see cracking from too-high spoke tension,
>but not from too-high tire pressure.

Mavic has a maximum recommended air pressure for their wheel/rims. It's
buried somewhere on their website and lower than you might think.


Chris Neary


"Science, freedom, beauty, adventure: what more could
you ask of life? Bicycling combined all the elements I
loved" - Adapted from a quotation by Charles Lindbergh

[Roger Zoul]

psycholist wrote:
:: "Roger Zoul" > wrote in message
:: ...
::: I've read a bit on this on Sheldon Brown's site, however, I'm
::: looking for a more precise answer, if possible.
:::
::: My road bike tires say that max inflation is 130 psi. Okay, before
::: my last 25 mile ride, I inflated my front tire to 130 psi, since I
::: wanted to roll easy. So I do the ride okay, get the home & put the
::: bike up w/ no problems. Next time I go for it, the front tire is
::: flat. Get the tube off to find it split several inches along the
::: inside seem, so it appears to me that this was due to over
::: inflation. Was it? And if so, could I have avoided this by
::: inflating to 125 psi, instead of 130 psi? It was a clear & sunny
::: day, so there was no need to have less air in the tire. How close
::: to max can one go, in general? Maybe a had a slightly bumb tube?
:::
::: Thanks.
:::
::
:: It's quite common for people to pump their tires right to the max
:: psi or even slightly beyond. I don't recommend going beyond, but I
:: know it's pretty commonly done by folks like triathletes and that
:: who believe they're reducing rolling resistance.
::
:: Sounds to me like you had a bumb tube, but I'd make sure your rim
:: tape is covering all the spoke holes on the rim and that there
:: aren't any exposed edges that could create a hole.

I did check the rim tape covering the spoke holes...all seems fine there.

::
:: One last thing. High psi isn't good for all wheels. Some of the
:: fancy, low-spoke count, light weight wheels can develop cracks at
:: the spoke holes if you keep the tire pressure too high.

Mine are by Specialized...those are low-spoke count wheels, too. However,
the tires are 700 x 26, so those aren't as lightweight as others, I'd think.

[Roger Zoul]

wrote:
:: Roger Zoul writes:
::
::: I've read a bit on this on Sheldon Brown's site, however, I'm
::: looking for a more precise answer, if possible.
::
::: My road bike tires say that max inflation is 130 psi. Okay, before
::: my last 25 mile ride, I inflated my front tire to 130 psi, since I
::: wanted to roll easy. So I do the ride okay, get the home & put the
::: bike up w/ no problems. Next time I go for it, the front tire is
::: flat. Get the tube off to find it split several inches along the
::: inside seem, so it appears to me that this was due to over
::: inflation. Was it? And if so, could I have avoided this by
::: inflating to 125 psi, instead of 130 psi? It was a clear & sunny
::: day, so there was no need to have less air in the tire. How close
::: to max can one go, in general? Maybe a had a slightly bum tube?
::
:: Tubes cannot split open in the tire from high pressure. Your tire
:: blew off the rim while you weren't there or you would have heard it.
:: You should probably run tires at 120psi or less, and don't expect to
:: descend steep braking hills at that pressure either.

You know....when I first went to get the bike and noticed the flat, the tire
was off the rim! I remember wondering how it could have come off like that,
rather than just going flat. BTW, on the day of my ride it was extremely
windy, and I'm a heavy guy. Maybe there was some rim heating.
::
:: http://draco.acs.uci.edu/rbfaq/FAQ/8b.4.html
::
:: This is not new.

I see. Thanks.

[David Kerber]

In article >,
says...
> >> One last thing. High psi isn't good for all wheels. Some of the fancy,
> >> low-spoke count, light weight wheels can develop cracks at the spoke holes
> >> if you keep the tire pressure too high.
> >
> >How does that happen? I can see cracking from too-high spoke tension,
> >but not from too-high tire pressure.
>
> Mavic has a maximum recommended air pressure for their wheel/rims. It's
> buried somewhere on their website and lower than you might think.

I understand why a rim might have a limit on pressure (at least for
clinchers), but this would seem to be a bead/rim sidewall issue, not a
spoke hole issue.

--
Dave Kerber
Fight spam: remove the ns_ from the return address before replying!

REAL programmers write self-modifying code.

[Art Harris]

"Roger Zoul"
> the tires are 700 x 26, so those aren't as lightweight as others, I'd think.

700 x 26 with a max pressure rating of 130 psi? That sounds very
unusual. Normally, max pressure ratings increase as the tire width
decreases.

What brand of tire is this?

Art Harris

[Roger Zoul]

Art Harris wrote:
:: "Roger Zoul"
::: the tires are 700 x 26, so those aren't as lightweight as others,
::: I'd think.
::
:: 700 x 26 with a max pressure rating of 130 psi? That sounds very
:: unusual. Normally, max pressure ratings increase as the tire width
:: decreases.
::
:: What brand of tire is this?

FRONT TIRE Specialized New Turbo Pro, 700 x 26c, kevlar bead

REAR TIRE Specialized New Turbo Pro, 700 x 26c, kevlar bead

[Rick Onanian]

On Tue, 9 Dec 2003 07:39:57 -0500, David Kerber
> wrote:
>In article >,
says...
>> >> One last thing. High psi isn't good for all wheels. Some of the fancy,
>> >> low-spoke count, light weight wheels can develop cracks at the spoke holes
>> >> if you keep the tire pressure too high.
>> >
>> >How does that happen? I can see cracking from too-high spoke tension,
>> >but not from too-high tire pressure.
>>
>> Mavic has a maximum recommended air pressure for their wheel/rims. It's
>> buried somewhere on their website and lower than you might think.
>
>I understand why a rim might have a limit on pressure (at least for
>clinchers), but this would seem to be a bead/rim sidewall issue, not a
>spoke hole issue.

I imagine that the pressure on the bead would result in some folding
pressure along the inside of the rim; and the spoke holes, right on
center, would be the weak point.
--
Rick Onanian

[[email protected]]

Rick Onanian writes:

>>>>> One last thing. High psi isn't good for all wheels. Some of
>>>>> the fancy, low-spoke count, light weight wheels can develop
>>>>> cracks at the spoke holes if you keep the tire pressure too
>>>>> high.

>>>> How does that happen? I can see cracking from too-high spoke
>>>> tension, but not from too-high tire pressure.

>>> Mavic has a maximum recommended air pressure for their
>>> wheel/rims. It's buried somewhere on their website and lower than
>>> you might think.

>> I understand why a rim might have a limit on pressure (at least for
>> clinchers), but this would seem to be a bead/rim sidewall issue,
>> not a spoke hole issue.

> I imagine that the pressure on the bead would result in some folding
> pressure along the inside of the rim; and the spoke holes, right on
> center, would be the weak point.

Since tires blow off at about 130psi, there is no reason for a rim not
to sustain such pressures. I believe the reason for giving a limit is
to prevent people from suing them for not warning that their rims will
not retain tires over a certain pressure. The rim can take it, but
can the rider, when the tire blows off?

Jobst Brandt

[Eric S. Sande]

>Since tires blow off at about 130psi, there is no reason for a rim not
>to sustain such pressures. I believe the reason for giving a limit is
>to prevent people from suing them for not warning that their rims will
>not retain tires over a certain pressure. The rim can take it, but
>can the rider, when the tire blows off?

I never have seen a properly inflated tire blow off an MA-2 or a CR-18.

I believe it could happen but I think you would have to have overinflated
to a degree and be braking hard in a descent to see it.

I've seen rims get very hot and steam come off them in hard braking,
or at least water vapor. I never saw a tire blow off.

Unless you count the most recent TDF. That was a tubular rolling off
the rim due to the glue melting, IMHO.

--

_______________________ALL AMIGA IN MY MIND_______________________
------------------"Buddy Holly, the Texas Elvis"------------------

[[email protected]]

Eric S. Sande writes:

>> Since tires blow off at about 130psi, there is no reason for a rim
>> not to sustain such pressures. I believe the reason for giving a
>> limit is to prevent people from suing them for not warning that
>> their rims will not retain tires over a certain pressure. The rim
>> can take it, but can the rider, when the tire blows off?

> I never have seen a properly inflated tire blow off an MA-2 or a
> CR-18.

> I believe it could happen but I think you would have to have
> over-inflated to a degree and be braking hard in a descent to see
> it.

I assure you that it has been don descending on MA-2 rims with IRC
700x25 tires pumped to 100 psi. I have done it and so have people
with whom I ride. This was after more than 100 miles of hilly riding.
We know how a poorly mounted tire feels. This was simple overheating.

> I've seen rims get very hot and steam come off them in hard braking,
> or at least water vapor. I never saw a tire blow off.

Tandem folks can tell you a lot about that if they tour in the
mountains. I have testified in suits against the bicycle industry by
such folks.

> Unless you count the most recent TDF. That was a tubular rolling
> off the rim due to the glue melting, IMHO.

That and other reasons.

Jobst Brandt

[Eric S. Sande]

>I have testified in suits against the bicycle industry by
>such folks.

Pehaps you could elaborate. Many of the newer people don't know
your crdentials.

--

_______________________ALL AMIGA IN MY MIND_______________________
------------------"Buddy Holly, the Texas Elvis"------------------

[archer]

In article >,
says...
> On Tue, 9 Dec 2003 07:39:57 -0500, David Kerber
> > wrote:
> >In article >,
> says...
> >> >> One last thing. High psi isn't good for all wheels. Some of the fancy,
> >> >> low-spoke count, light weight wheels can develop cracks at the spoke holes
> >> >> if you keep the tire pressure too high.
> >> >
> >> >How does that happen? I can see cracking from too-high spoke tension,
> >> >but not from too-high tire pressure.
> >>
> >> Mavic has a maximum recommended air pressure for their wheel/rims. It's
> >> buried somewhere on their website and lower than you might think.
> >
> >I understand why a rim might have a limit on pressure (at least for
> >clinchers), but this would seem to be a bead/rim sidewall issue, not a
> >spoke hole issue.
>
> I imagine that the pressure on the bead would result in some folding
> pressure along the inside of the rim; and the spoke holes, right on
> center, would be the weak point.

True; I hadn't thought of that, but in that case, *higher* spoke
counts would be worse than *low* ones (except of course that low spoke
count wheels are typically of lighter construction as well).

--
Dave Kerber
Fight spam: remove the ns_ from the return address before replying!

REAL programmers write self-modifying code.

[archer]

In article >,
says...

....

> > I imagine that the pressure on the bead would result in some folding
> > pressure along the inside of the rim; and the spoke holes, right on
> > center, would be the weak point.
>
> Since tires blow off at about 130psi, there is no reason for a rim not
> to sustain such pressures. I believe the reason for giving a limit is
> to prevent people from suing them for not warning that their rims will
> not retain tires over a certain pressure. The rim can take it, but
> can the rider, when the tire blows off?

Do you mean to say that there is no way that any clinchers can handle
above 130 psi?

--
Dave Kerber
Fight spam: remove the ns_ from the return address before replying!

REAL programmers write self-modifying code.

[Anine Swart]

I found out after complete exasperation that Continental Avenues,
..26x1.3 can be inflated WAY WAY over their max. (I was using Conti
tubes as well)

The avenues are horrendously hard to seat well since the bead slips
off the rim to the inside and doesn't completely climb back on on
inflation. Usually it works fairly well if you smear a little
dishwashing liquid on the inside of the trouble spot and over inflate
a little bit but this time the tyre stubbornly refused to climb back
onto the rim. The sidewall rating is 80PSI max and I inflated them to
120PSI before the damn thing went "TWANG" and seated smoothly.

Ofcourse when it went "TWANG" at last, I nearly wet myself, thinking
for a split second it had exploded :P

I didn't attempt to ride with the over inflated tyre though :)

Anine

"Roger Zoul" > wrote in message >...
> I've read a bit on this on Sheldon Brown's site, however, I'm looking for a
> more precise answer, if possible.
>
> My road bike tires say that max inflation is 130 psi. Okay, before my last
> 25 mile ride, I inflated my front tire to 130 psi, since I wanted to roll
> easy. So I do the ride okay, get the home & put the bike up w/ no problems.
> Next time I go for it, the front tire is flat. Get the tube off to find it
> split several inches along the inside seem, so it appears to me that this
> was due to over inflation. Was it? And if so, could I have avoided this by
> inflating to 125 psi, instead of 130 psi? It was a clear & sunny day, so
> there was no need to have less air in the tire. How close to max can one
> go, in general? Maybe a had a slightly bumb tube?
>
> Thanks.