Wheelchair tyre problem

Tom Orr said:

I have borrowed a wheelchair for a couple of weeks (long story) but
one of the 20" tyres keeps popping off the rim. The recommended
pressure is 30 PSI but even at 20 PSI it pops off after a few hours.
I don't want to have to hunt down a new tyre; they are strange, grey,
balloon type things which are probably hard to find. Is any way to
prevent this from happening?

It sounds like someone has put the wrong size tyre (fraction too big
diameter) on the rims.

Though without technical details, its hard to be sure.

- Nigel

--
Nigel Cliffe,
Webmaster at http://www.2mm.org.uk/

Tom Orr said:

I have borrowed a wheelchair for a couple of weeks (long story) but one of
the 20" tyres keeps popping off the rim. The recommended pressure is 30
PSI but even at 20 PSI it pops off after a few hours. I don't want to have
to hunt down a new tyre; they are strange, grey, balloon type things which
are probably hard to find. Is any way to prevent this from happening?

There are 3 different rims called "20 inch", they are 451, 419 and 406mm
in diameter. You possibly have a 419 tyre on a 406 rim, which would
appear to be a loose fit, but blow off quickly. Your only cure is to get
tyres of the correct size for the rim.

The tyre size should be moulded into the side-wall, but you might have to
measure the rim to find out what it is, not all of them are marked. Wrap
a piece of string around the rim where the tyre sits (not at the top of
the rim, nor in the bottom of the well where the spoke heads are), and
check that against a tape measure.

Mike

On 07/23/2005 13:55:38 'Tom Orr said:

I have borrowed a wheelchair for a couple of weeks (long story) but one of
the 20" tyres keeps popping off the rim. The recommended pressure is 30
PSI but even at 20 PSI it pops off after a few hours. I don't want to
have to hunt down a new tyre; they are strange, grey, balloon type things
which are probably hard to find. Is any way to prevent this from
happening?

Quoted message said:

Thanks in advance

Have you checked to see if the bead on the tyre is intact?

--

Buck

I would rather be out on my Catrike

http://www.catrike.co.uk

Buck wrote:

<snipped>

Quoted message said:

Have you checked to see if the bead on the tyre is intact?

Yes. The rubber around the bead is partially stripped and that seems to be
the cause of the problem. I thought of building it up with a piece of old
inner tube. However I have found a supplier of these odd tyres so I have
ordered a new one for £14 though it won't come until Tuesday.

Tom.

On 07/24/2005 09:02:17 'Tom Orr said:

Buck wrote:

Quoted message said:

Quoted message said:

Have you checked to see if the bead on the tyre is intact?

Quoted message said:

Yes. The rubber around the bead is partially stripped and that seems to
be the cause of the problem. I thought of building it up with a piece of
old inner tube. However I have found a supplier of these odd tyres so I
have ordered a new one for £14 though it won't come until Tuesday.

I spent a few months in a wheelchair some years ago, the chair I hired
was a lightweight one with Schwalbe tyres, funnily enough I have a
preference for thos tyres on the trikes I sell, I had a problem with
the NHS chair I had, with a broken bead, I assume it was due to the
insistance on running the chair with flats all the time.
--

Buck

I would rather be out on my Catrike

http://www.catrike.co.uk

Mike Causer said:

There are 3 different rims called "20 inch", they are 451, 419 and
406mm in diameter. You possibly have a 419 tyre on a 406 rim, which
would appear to be a loose fit, but blow off quickly. Your only cure
is to get tyres of the correct size for the rim.

To say nothing of 440...

--
Dave Larrington - <http://www.legslarry.beerdrinkers.co.uk/>
Every establishment needs an opposition.