Overinflated tires

[Earl Bollinger]

"Ken M" > wrote in message
...
>I know that it is not recommended to over inflate your tire, but I have had
>the tires on my bike inflated up to around 90psi, they are rated for 85psi.
>So I was wondering is there a "safe" limit to how much you can over inflate
>tires, or is it more or less a per tire type of thing. Meaning one brand /
>model of tire may be able to with stand a higher pressure than a different
>brand / model, even if they are both "rated" for the same maximum pressure.
>
> Ken "pump them till they pop" M.
> --
> When I see an adult on a bicycle, I do not despair for the future of the
> human race. ~H.G. Wells
>
Well normally being a bit over won't hurt anything. Especially in the winter
when it is cold outside.
But if you have the stamped steel rims, the tire's bead may pop loose at
higher pressures than normal causing the bead to come off the rim. These
steel rims don't have a sharp defined edge for the tire's bead to lock into
good.
A sharp rock damaging the tire's cord or plies could lead to a delayed
blowout of the tube when you least expect it. Same for sharp edges like
uneven road slabs or sidewalk slabs that might damage the internal plies of
the tire. In this case a sharp rock doesn't punture all the way through to
the tube, but falls short. later the tube's pressure causes the tube to blow
out as it isn't supported over the damaged spot on the tire. A tire at lower
pressures has more give to it so it suffers less or little damage from the
sharp rock.
On a hot summer day with hot pavement, the tire's pressure could skyrocket
causing a blowout.
Really high pressures like 140psi or 160psi or so, could cause the rim's
braking surface sides to blow off the wheel, pretty spectacular to
experience if you survive the heart attack. Basically the rim's sides get
worn down from useage, you put on a new high pressure tire and pump that
sucker up to 160psi because the tire's max rating says you can. Boom goes
the rim side on you suddenly, because it is too weak now.
In track bike racing, they might pump up tubulars to something fantastic
like 200psi. But at these pressures the slightest damage to the tire's plies
cord could blow them out, sometimes they've blown out just bumping another
wheel just waiting for the race start.

[Ken M]

I know that it is not recommended to over inflate your tire, but I have
had the tires on my bike inflated up to around 90psi, they are rated for
85psi. So I was wondering is there a "safe" limit to how much you can
over inflate tires, or is it more or less a per tire type of thing.
Meaning one brand / model of tire may be able to with stand a higher
pressure than a different brand / model, even if they are both "rated"
for the same maximum pressure.

Ken "pump them till they pop" M.
--
When I see an adult on a bicycle, I do not despair for the future of the
human race. ~H.G. Wells

[rdclark]

Ken M wrote:
> I know that it is not recommended to over inflate your tire, but I have
> had the tires on my bike inflated up to around 90psi, they are rated for
> 85psi. So I was wondering is there a "safe" limit to how much you can
> over inflate tires, or is it more or less a per tire type of thing.
> Meaning one brand / model of tire may be able to with stand a higher
> pressure than a different brand / model, even if they are both "rated"
> for the same maximum pressure.

Since there are other critical variables - rider weight, rim width,
etc. - that can have a profound effect on whether a given tire will
fail (and how) at a given pressure, I think you'd need a lab, a huge
budget, and an infinite number of monkeys to figure this out.

But I bet that there is a very large safety factor built into all these
psi ratings, mandated by lawyers. I doubt that a few percent matters.

RichC

[what does THIS button do?]

i blew out an expensive Nokian Extreme 294 studded tire by over
inflating, i think. I ran it around 100~110 psi (rated a lot lower),
rode 15 miles daily; afer about three months of this, the sidewall
seperated from the bead.:-( :-( :-( Thankfully, it happened at the
office and not in the arctic bufu.

Painful lesson, cost of tuition: $100.

I now recommend paying attention to the figures on the side of the
tire.

..max
not so smart.

[Human powered]

"Ken M" > wrote in message
...
>I know that it is not recommended to over inflate your tire, but I have had
>the tires on my bike inflated up to around 90psi, they are rated for 85psi.
>So I was wondering is there a "safe" limit to how much you can over inflate
>tires, or is it more or less a per tire type of thing. Meaning one brand /
>model of tire may be able to with stand a higher pressure than a different
>brand / model, even if they are both "rated" for the same maximum pressure.
>
> Ken "pump them till they pop" M.
> --
> When I see an adult on a bicycle, I do not despair for the future of the
> human race. ~H.G. Wells
>

I don't think the accuracy of one pump to another would be better than 5
lbs. So I can't imagine that it's a problem. Although, if I were to want
much more I'd get something rated for what I want.

[M Powell]

What we keep reading about lately are the advantages to slightly
under-inflating road bike tires (100 rear, 90 front for most tires). Stated
benefits: You get more contact with road, softer ride, better cornering...

What advantages are you after by over-inflating? What's the allure?

-- M Powell

"Ken M" > wrote in message
...
>I know that it is not recommended to over inflate your tire, but I have had
>the tires on my bike inflated up to around 90psi, they are rated for 85psi.
>So I was wondering is there a "safe" limit to how much you can over inflate
>tires, or is it more or less a per tire type of thing. Meaning one brand /
>model of tire may be able to with stand a higher pressure than a different
>brand / model, even if they are both "rated" for the same maximum pressure.
>
> Ken "pump them till they pop" M.
> --
> When I see an adult on a bicycle, I do not despair for the future of the
> human race. ~H.G. Wells
>

[Tom Keats]

In article >,
Ken M > writes:
> I know that it is not recommended to over inflate your tire, but I have
> had the tires on my bike inflated up to around 90psi, they are rated for
> 85psi. So I was wondering is there a "safe" limit to how much you can
> over inflate tires, or is it more or less a per tire type of thing.
> Meaning one brand / model of tire may be able to with stand a higher
> pressure than a different brand / model, even if they are both "rated"
> for the same maximum pressure.

My 26x1.5" IRC Metros are rated to max pressure: 40 psi.
I've been pumping 'em up to 60 since I got them (about a
year ago) with no ill effects. And that's on several
thousand kilometers and some bunny-hopping on a
heavily-rigged bike.

Anyways, I notice whenever folks here suggest a list of
accessories to tyro or returning-to-the-avocation riders,
cycloputers get lots of recommendation. But nobody ever
suggests a hand-held pressure gauge.


cheers,
Tom

--
-- Nothing is safe from me.
Above address is just a spam midden.
I'm really at: tkeats [curlicue] vcn [point] bc [point] ca

[Ken M]

M Powell wrote:
> What we keep reading about lately are the advantages to slightly
> under-inflating road bike tires (100 rear, 90 front for most tires). Stated
> benefits: You get more contact with road, softer ride, better cornering...
>
> What advantages are you after by over-inflating? What's the allure?
>

Well I have read that the rolling resistance is less for a tire with a
high air pressure than the same tire with a lower pressure. Lower rr
means less energy needed to maintain a set speed. Unless the laws of
physics have changed.

Ken
--
When I see an adult on a bicycle, I do not despair for the future of the
human race. ~H.G. Wells

[Ken M]

Tom Keats wrote:

>
> My 26x1.5" IRC Metros are rated to max pressure: 40 psi.
> I've been pumping 'em up to 60 since I got them (about a
> year ago) with no ill effects. And that's on several
> thousand kilometers and some bunny-hopping on a
> heavily-rigged bike.
>
WOW that seems a bit higher than I might go in my road tires. I was
thinking about 10 to 15%.

> Anyways, I notice whenever folks here suggest a list of
> accessories to tyro or returning-to-the-avocation riders,
> cycloputers get lots of recommendation. But nobody ever
> suggests a hand-held pressure gauge.

I have a nice digital gauge, in addition to the built in gauge on the pump.

Ken
--
When I see an adult on a bicycle, I do not despair for the future of the
human race. ~H.G. Wells

[M Powell]

I'm a subscriber to RoadBikeRider.com, and also subscribe to their thought
that rolling resistance is only one factor, and probably not a very telling
one, in tire pressure. Here's a quote:
"overinflation causes only bad things on the road -- tread cuts, fast wear,
chattering in corners, jack-hammer shocks from road irregularities. As we've
often stated, even inflating to the recommended max is usually a mistake.
For most riders on typical 700x23C tires, a front pressure of 90-95 psi and
a rear around 100 psi will maximize tire life, bike handling and comfort.
The only reason to go higher is if the road is so bad or your weight is so
high that these moderate pressures allow pinch flats."

YMMV

[Tom Keats]

In article >,
Ken M > writes:

> I have a nice digital gauge, in addition to the built in gauge on the pump.

I don't trust gauges that come built-in with pumps.
And I figure it's generally good to get a "2nd opinion".


cheers,
Tom

--
-- Nothing is safe from me.
Above address is just a spam midden.
I'm really at: tkeats [curlicue] vcn [point] bc [point] ca

[Andy Gee]

Ken M > wrote in news:FKCdneII3JLcWTveRVn-
:

> I know that it is not recommended to over inflate your tire, but I have
> had the tires on my bike inflated up to around 90psi, they are rated for
> 85psi. So I was wondering is there a "safe" limit to how much you can
> over inflate tires, or is it more or less a per tire type of thing.
> Meaning one brand / model of tire may be able to with stand a higher
> pressure than a different brand / model, even if they are both "rated"
> for the same maximum pressure.
>
> Ken "pump them till they pop" M.

Let me add my voice to the probable chorus of "watch-outs:"

I can't tell you how many tires I blew by overinflating. I'm the kind of
guy that viscerally can't stand to look down and see the slightest bit of
pudge in a tire. That's both because of aesthetics and rolling resistance,
in that order. But finally i learned to accept the reality when a blow-out
lost an irreplaceable tire from a rare bicycle.

--ag

[Zoot Katz]

On Mon, 19 Dec 2005 15:40:39 -0800,
(Tom Keats) wrote:

>In article >,
> Ken M > writes:
>
>> I have a nice digital gauge, in addition to the built in gauge on the pump.
>
>I don't trust gauges that come built-in with pumps.
>And I figure it's generally good to get a "2nd opinion".
>
My tire gauge is an old Dunlop No.17. It measures 50 to 140 psi. in
ten pound increments. At 70 psi it still correlates with the gauge on
my much newer Beto pump.

I usually check tires before riding by putting my weight on the handle
bar or saddle and noting the sidewall deflection. With butyl tubes,
they need topping-up about once per week.
--
zk

[Michael Warner]

On Tue, 20 Dec 2005 01:36:59 GMT, Andy Gee wrote:

> I can't tell you how many tires I blew by overinflating. I'm the kind of
> guy that viscerally can't stand to look down and see the slightest bit of
> pudge in a tire.

If the tyre isn't squashing, you might as well be riding on solid rubber.

--
Home page: http://members.westnet.com.au/mvw

[[email protected]]

Ken M wrote:
> I know that it is not recommended to over inflate your tire, but I have
> had the tires on my bike inflated up to around 90psi, they are rated for
> 85psi. So I was wondering is there a "safe" limit to how much you can
> over inflate tires, or is it more or less a per tire type of thing.
> Meaning one brand / model of tire may be able to with stand a higher
> pressure than a different brand / model, even if they are both "rated"
> for the same maximum pressure.
>
> Ken "pump them till they pop" M.

I had tire problems on a long tour. We were using Continential Top
Touring 2000 tires, which have a bit of a reputation for sidewall
problems (which I _thought_ had been fixed). Anyway, we had at least
two tires get bad bubbles in the sidewalls, and I figured it may have
been because I accidentally overinflated.

In summary, it may depend on the specific tire.

- Frank Krygowski

[andy gee]

Michael Warner > wrote in
:

> On Tue, 20 Dec 2005 01:36:59 GMT, Andy Gee wrote:
>
>> I can't tell you how many tires I blew by overinflating. I'm the
>> kind of guy that viscerally can't stand to look down and see the
>> slightest bit of pudge in a tire.
>
> If the tyre isn't squashing, you might as well be riding on solid
> rubber.
>

Is that a bad thing, if you get the rolling resistance of a solid torus
for the weight of one that's hollow?

I notice that a guy that weighs about 150 - 160 lbs, on a light bike
with high-pressure tires, bent all the way forward, doesn't squish. I'm
175 with a formerly lightweight bike, usually bent forward, and I pudge
out a little bit, but I've learned to accept it.

--ag

[Andrew Price]

On Mon, 19 Dec 2005 17:56:56 -0500, Ken M > wrote:

[---]

>I have a nice digital gauge, in addition to the built in gauge on the pump.

A Topeak?

[Ken M]

Andrew Price wrote:
> On Mon, 19 Dec 2005 17:56:56 -0500, Ken M > wrote:
>
> [---]
>
>
>>I have a nice digital gauge, in addition to the built in gauge on the pump.
>
>
> A Topeak?

Yes a Topeak. Is that a bad thing???

Ken
--
On the internet, nobody knows you're a jerk - unless you act like a jerk
on the internet too. - Quote modified by Ken M.

[Michael Warner]

On Tue, 20 Dec 2005 11:34:33 -0600, andy gee wrote:

> Is that a bad thing, if you get the rolling resistance of a solid torus
> for the weight of one that's hollow?

Your rolling resistance might be wonderfully low, but you'll be
bouncing on the tiniest bumps and have minimal grip, so it's
pointless.

--
Home page: http://members.westnet.com.au/mvw

[Pat Lamb]

Tom Keats wrote:
>
> Anyways, I notice whenever folks here suggest a list of
> accessories to tyro or returning-to-the-avocation riders,
> cycloputers get lots of recommendation. But nobody ever
> suggests a hand-held pressure gauge.

My Silca floor pump gauge is so good, I hardly ever use my hand-held!

(Or at least I guess it is. I've never seen the benefit in comparing
one calibration-unknown reading to the reading from another
calibration-unknown instrument.)

Pat

[[email protected]]

Pat Lamb wrote:
> Tom Keats wrote:
> >
> > Anyways, I notice whenever folks here suggest a list of
> > accessories to tyro or returning-to-the-avocation riders,
> > cycloputers get lots of recommendation. But nobody ever
> > suggests a hand-held pressure gauge.
>
> My Silca floor pump gauge is so good, I hardly ever use my hand-held!
>
> (Or at least I guess it is. I've never seen the benefit in comparing
> one calibration-unknown reading to the reading from another
> calibration-unknown instrument.)
>
> Pat

Well if they agree the chances are reasonably good that they are both
correct. If they disagree then one or both are wrong. Of course you
don't know which or by how much but you do know that you may have a
problem
John Kane, Kingston ON Canada

[Michael]

M Powell wrote:
>
> What we keep reading about lately are the advantages to slightly
> under-inflating road bike tires (100 rear, 90 front for most tires). Stated
> benefits: You get more contact with road, softer ride, better cornering...
>
> What advantages are you after by over-inflating? What's the allure?
>
> -- M Powell
>
> "Ken M" > wrote in message
> ...
> >I know that it is not recommended to over inflate your tire, but I have had
> >the tires on my bike inflated up to around 90psi, they are rated for 85psi.
> >So I was wondering is there a "safe" limit to how much you can over inflate
> >tires, or is it more or less a per tire type of thing. Meaning one brand /
> >model of tire may be able to with stand a higher pressure than a different
> >brand / model, even if they are both "rated" for the same maximum pressure.
> >
> > Ken "pump them till they pop" M.
> > --
> > When I see an adult on a bicycle, I do not despair for the future of the
> > human race. ~H.G. Wells
> >


I run both front and rear at 100 PSI, their rating. They arey 27 x 1.25" and do
ride rough at that pressure, compared to 80-90 PSI (don't ask) but they're also
harder to roll. Noticeably so.

In fact, every time I feel like I'm dragging sandbags I know I've neglected
checking tire pressure too long. One day, just after that very thought popped
into my mind, the rear tire blew out. Oh yeah ... underinflated. I finally
learned my lesson: just go ahead and screw on the pump before every ride; don't
bother checking pressure first, because it'll definitely be low.

--
Michael