# Pressure!

I noticed that someone said he rode a uni with a tire pressure of say 50
pounds. I weigh about 135lbs (sorry folks, i have forgotten my metric
conversion on that one i think about 60 kg???) anyway I inflate my tire to
rock hard. I never really measure it but i think it’s between 80 and 90 psi
(not even gonna try the conversion to kg/cc .) I have grown to like no
squish in the tire, and if you’de check out the home page i think you’de
find most unicyclists agree that a tire that says “inflate to 40PSI max”
really means “inflate to 90 psi max.” Believe it or not you’ll wear em out
in less time at the much higher pressures.

My thoughts on the matter… Karl!

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Re: Pressure!

Sun, 24 Sep 1995 00:02:04 -0500 unimail@njackn.com wrote:

> I noticed that someone said he rode a uni with a tire pressure of say 50
> pounds. I weigh about 135lbs (sorry folks, i have forgotten my metric
> conversion on that one i think about 60 kg???) anyway I inflate my tire to
> rock hard. I never really measure it but i think it’s between 80 and 90
> psi (not even gonna try the conversion to kg/cc .) I have grown to like
> no squish in the tire, and if you’de check out the home page i think
> you’de find most unicyclists agree that a tire that says "inflate to 40PSI
> max" really means “inflate to 90 psi max.” Believe it or not you’ll wear
> em out in less time at the much higher pressures.
>

I agreee with Karl. I run a minimum of 50 lb in a tyre, try to fit as much in as
I can, usually 70-80 lbs. I have found one tyre in the past thats handles 120
lb. No squish to me is superior handling and responsiveness. Also a hard tyre at
these pressures protect the tube when going down steps.

I’m 90 Kgs (in winter months!)

• Earth name: Ross Mackintosh * Email: romack@midland.co.nz *
• Phone: (07) 839 9005 * Batfone: (025) 761 141 * Fax: (07) 839 9006 *
• Snail: Box 776, Hamilton, New Zealand *

Re: Pressure! ( Blast Hazard )

On Mon, 25 Sep 1995, Ross Mackintosh wrote:

>
> I agreee with Karl. I run a minimum of 50 lb in a tyre, try to fit as much in
> as I can, usually 70-80 lbs. I have found one tyre in the past thats

I’ve got a newer Schwinn ( blue-rim) and on it and one earlier Schwinn model I
had much trouble with high pressure in the tire – even to as low as 40 psi. The
tire would pop off the rim, exposing unconstrained rubber, which would either
bubble ominously, or, much to the detriment of the weak hearts in a college
classroom in which I parked my uni. explode loudly.

While observing the pale faces around me after the blast was entertaining,
frequently purchasing new tubes is not.

Is this a common problem, or it is just me? If there are others with this same
experience, it may be wise to be cautious before inflating the tube to as high
as 120psi.

eric.

Re: Pressure! ( Blast Hazard )

Eric Busboom <ebusboom@qualcomm.com> (EB) writes:

EB> I’ve got a newer Schwinn ( blue-rim) and on it and one earlier Schwinn model
EB> I had much trouble with high pressure in the tire – even to as low as 40
EB> psi. The tire would pop off the rim, exposing unconstrained rubber, which
EB> would either bubble ominously, or, much to the detriment of the weak hearts
EB> in a college classroom in which I parked my uni. explode loudly.

I have the same model and keep the tire inflated to around 55-60 psi without
any problems.

Re: Pressure!

unimail@njackn.com wrote:

: squish in the tire, and if you’de check out the home page i think you’de find
: most unicyclists agree that a tire that says “inflate to 40PSI max” really
: means “inflate to 90 psi max.” Believe it or not you’ll wear em out in less
: time at the much higher pressures.

I too ride with a tyre as hard as the pump will get it. Something to note about
pressure specs on the side of tyres (this is true in the UK, but I don’t know
about elsewhere) is that all the manufacturer has to do is inflate the tyre to
twice the quoted pressure and show that it doesn’t blow off the rim. This means
1: there is no good reason for paying much attention to the quoted value, and 2:
it is relatively easy to get your tyre into a situation it has never been
tested at.

I don’t think the wear rate varies much, once the tyre is above ‘reasonably
hard’, but I did have one tyre where the bead pulled away from the main body of
the tread. I noticed this and, since the tear was small, sort of bodged a patch
with some canvas. Then, cyling allong one day a couple of weeks later (all of a
sudden) the inner-tube shot out the hole and made a vast grotesque sort of
balloon outside the tyre. It was quite remarkable.

regards, Ian Smith

Re: Pressure!

unimail@njackn.com wrote:
>most unicyclists agree that a tire that says “inflate to 40PSI max” really
>means “inflate to 90 psi max.”

I did inflate a new Miyata 24" tire (about 40 psi max.) to 90 psi. It lasted
about one day, when the cords in one sidewall broke, allowing the tube to split
half several feet making it useless as well.

>Believe it or not you’ll wear em out in less time at the much higher pressures.

Sometimes the pressure can to too high and the tire may not have a chance
to wear out.

After losing a new 40 psi tire at 90 psi, 70 psi for such a tire is my own new
personal maximum for such a tire. That’s still a 75% overinflation!

Sincerely,

Ken Fuchs <kfuchs@winternet.com

Re: Pressure! ( Blast Hazard )

Eric Busboom <ebusboom@qualcomm.com> writes:
>I’ve got a newer Schwinn ( blue-rim) and on it and one earlier Schwinn model I
>had much trouble with high pressure in the tire – even to as low as 40 psi.
>The tire would pop off the rim, exposing unconstrained rubber, which would
>either bubble ominously, or, much to the detriment of the weak hearts in a
>college classroom in which I parked my uni. explode loudly.

I know that Schwinn made their own bicycle rims on which only schwinn tires
would fit properly. This may apply to their uni’s also, but I don’t know for
certain as I have never had to replace my OEM schwinn tire. However, if it does
apply, maybe a non-schwinn-rim-sized tire could be causing your problem.

Or maybe you’ve broken the metal reinforcing wires in the bead of the tire or
the rubber around them. That has happened to me on bicycles and caused the
blowouts you described.

Mark

Re: Pressure!

Ken Fuchs <kfuchs@winternet.com> writes:
> After losing a new 40 psi tire at 90 psi, 70 psi for such a tire is my own new
> personal maximum for such a tire. That’s still a 75% overinflation!

I was talking to a freestyle BMX’er today, and I noticed that his tyres were
rock solid (and I do mean rock solid!), his tyres were rated at 100psi (20 inch
x 1.75) and he overinflated them up to about 120 to get a bit more firmness…
apparently you can get tyres rated up to about 150psi, but they are quite
expensive. He didn’t seem to think they were available in 24" diameter though,
its mostly the racers who use that size wheels and they don’t need the hardness.

I will try and look for one though, I’m getting to need a new tyre soon so a
higher rated one would be good. Something else he told me about, is you can get
a shield that goes inside the tyre, its like a sheet of stiff rubber and
protects your inner tube from thorns etc…

]ain