In an earlier contribution to this discussion,
John wrote:

"Chris Lawrence" wrote in message
...
Roger Mills wrote:

And presumably you also have a system of elaborate mirrors so that
you can
watch the tyres while in motion?

S'okay, I was taking the ****. You just set it up so good!

As others have testified, if these very low profile tyres lose
pressure, they're knackered in very short order!

I can't imagine it does the wheels any favours either

Chris

I thought some cars use the antilock braking sensors to compare the
speed of each wheel - over a significant distance. If one is
revolving at a different speed consistently then it warns of a
puncture

Dunno. Mine doesn't. Besides which, I don't know whether that would work.
There is a school of thought which says that the distance covered per wheel
rev is determined by the amount of tread laid on the road - rather than 2 x
Pi x standing height. If that is that case, a soft tyre would not rotate at
a higher speed than an inflated one.
--
Cheers,
Roger
______
Email address maintained for newsgroup use only, and not regularly
monitored.. Messages sent to it may not be read for several weeks.
PLEASE REPLY TO NEWSGROUP!

"The Natural Philosopher" wrote in message
...
John wrote:
"Chris Lawrence" wrote in message
...
Roger Mills wrote:

And presumably you also have a system of elaborate mirrors so that you
can
watch the tyres while in motion?
S'okay, I was taking the ****. You just set it up so good!

As others have testified, if these very low profile tyres lose
pressure,
they're knackered in very short order!
I can't imagine it does the wheels any favours either

Chris

I thought some cars use the antilock braking sensors to compare the speed
of each wheel - over a significant distance. If one is revolving at a
different speed consistently then it warns of a puncture
That quite clever. Does it warn of four punctures while you are going
round a roundabout? Or one, when one wheel is spinning in the verge? :-)

No, that's why he said "over a significant distance" and "consistently". The
clue is in the words )


--
Bob Mannix
(anti-spam is as easy as 1-2-3 - not)

Bob Mannix wrote:
"The Natural Philosopher" wrote in message
...
John wrote:
"Chris Lawrence" wrote in message
...
Roger Mills wrote:

And presumably you also have a system of elaborate mirrors so that you
can
watch the tyres while in motion?
S'okay, I was taking the ****. You just set it up so good!

As others have testified, if these very low profile tyres lose
pressure,
they're knackered in very short order!
I can't imagine it does the wheels any favours either

Chris
I thought some cars use the antilock braking sensors to compare the speed
of each wheel - over a significant distance. If one is revolving at a
different speed consistently then it warns of a puncture
That quite clever. Does it warn of four punctures while you are going
round a roundabout? Or one, when one wheel is spinning in the verge? :-)

No, that's why he said "over a significant distance" and "consistently". The
clue is in the words )


So no use for rallying then ;-)

IIRC F1 cars use some kind of ride height sensing..any assymmetry in the
hat when going straight, is a puncture..

http://autospeed.com/cms/A_1267/article.html

Chris

I thought some cars use the antilock braking sensors to compare the
speed of each wheel - over a significant distance. If one is
revolving at a different speed consistently then it warns of a
puncture

Dunno. Mine doesn't. Besides which, I don't know whether that would work.
There is a school of thought which says that the distance covered per
wheel rev is determined by the amount of tread laid on the road - rather
than 2 x Pi x standing height. If that is that case, a soft tyre would not
rotate at a higher speed than an inflated one.
--
Cheers,
Roger
______

A lengthy article he

http://www-nrd.nhtsa.dot.gov/pdf/nrd.../05-0082-O.pdf

In an earlier contribution to this discussion,
John wrote:

Chris

I thought some cars use the antilock braking sensors to compare the
speed of each wheel - over a significant distance. If one is
revolving at a different speed consistently then it warns of a
puncture

Dunno. Mine doesn't. Besides which, I don't know whether that would
work. There is a school of thought which says that the distance
covered per wheel rev is determined by the amount of tread laid on
the road - rather than 2 x Pi x standing height. If that is that
case, a soft tyre would not rotate at a higher speed than an
inflated one. --
Cheers,
Roger
______

A lengthy article he

http://www-nrd.nhtsa.dot.gov/pdf/nrd.../05-0082-O.pdf


Thanks - two very useful articles for explaining the technology.

Using the existing ABS speed sensors is clearly cheaper than having
pressure/temperature sensors in the wheels - but has to be designed into the
car rather than being suitable for after-market use.

I'd still like to find someone who is using an after-market pressure
monitoring system in the UK - in order to find out what is available, and
whether it works ok. Surely there must be *somebody*?!
--
Cheers,
Roger
______
Email address maintained for newsgroup use only, and not regularly
monitored.. Messages sent to it may not be read for several weeks.
PLEASE REPLY TO NEWSGROUP!

On Fri, 12 Sep 2008 12:58:02 +0100 Roger Mills wrote :
There is a school of thought which says that the distance covered per wheel
rev is determined by the amount of tread laid on the road - rather than 2 x
Pi x standing height. If that is that case, a soft tyre would not rotate at
a higher speed than an inflated one.

The article referenced in another post says "The rolling radius of the tire
becomes smaller in proportion to the rate of deflation and therefore the
wheel speed of the deflated tire increases."

Surely if the length of the tread is 1.5m (and if it's a steel belt radial or
similar so won't change with inflation/deflation), travelling this distance
causes the wheel to rotate once whether fully inflated or running on the rim?

--
Tony Bryer SDA UK 'Software to build on' http://www.sda.co.uk

In an earlier contribution to this discussion,
Tony Bryer wrote:

On Fri, 12 Sep 2008 12:58:02 +0100 Roger Mills wrote :
There is a school of thought which says that the distance covered
per wheel rev is determined by the amount of tread laid on the road
- rather than 2 x Pi x standing height. If that is that case, a soft
tyre would not rotate at a higher speed than an inflated one.

The article referenced in another post says "The rolling radius of
the tire becomes smaller in proportion to the rate of deflation and
therefore the wheel speed of the deflated tire increases."

Surely if the length of the tread is 1.5m (and if it's a steel belt
radial or similar so won't change with inflation/deflation),
travelling this distance causes the wheel to rotate once whether
fully inflated or running on the rim?

That's my feeling too! But them what make pressure monitors based on change
in radius seem to be claiming otherwise.
--
Cheers,
Roger
______
Email address maintained for newsgroup use only, and not regularly
monitored.. Messages sent to it may not be read for several weeks.
PLEASE REPLY TO NEWSGROUP!

Tony Bryer wrote:
On Fri, 12 Sep 2008 12:58:02 +0100 Roger Mills wrote :

There is a school of thought which says that the distance covered per wheel
rev is determined by the amount of tread laid on the road - rather than 2 x
Pi x standing height. If that is that case, a soft tyre would not rotate at
a higher speed than an inflated one.


The article referenced in another post says "The rolling radius of the tire
becomes smaller in proportion to the rate of deflation and therefore the
wheel speed of the deflated tire increases."

Surely if the length of the tread is 1.5m (and if it's a steel belt radial or
similar so won't change with inflation/deflation), travelling this distance
causes the wheel to rotate once whether fully inflated or running on the rim?

With lower pressure, the tread gaps will be able to close up a little,
which will change the 'tread length' more obviously than it will change
the 'rolling radius'. The article is claiming a 3mm /1% difference,
which seems plausible, but you would want to cover a long distance
before deciding the difference in rotation wasn't due to roundabouts.

Tony Bryer wrote:
On Fri, 12 Sep 2008 12:58:02 +0100 Roger Mills wrote :
There is a school of thought which says that the distance covered per wheel
rev is determined by the amount of tread laid on the road - rather than 2 x
Pi x standing height. If that is that case, a soft tyre would not rotate at
a higher speed than an inflated one.

The article referenced in another post says "The rolling radius of the tire
becomes smaller in proportion to the rate of deflation and therefore the
wheel speed of the deflated tire increases."

Surely if the length of the tread is 1.5m (and if it's a steel belt radial or
similar so won't change with inflation/deflation), travelling this distance
causes the wheel to rotate once whether fully inflated or running on the rim?

Not quite.

The outer layer of tread can be fairly expanded on a fully inflated
tyre, or rather compressed on a rather deflated one.

Also you can get slip under traction..

In uk.d-i-y, Nick Finnigan wrote:
Tony Bryer wrote:
On Fri, 12 Sep 2008 12:58:02 +0100 Roger Mills wrote :

There is a school of thought which says that the distance covered per
wheel rev is determined by the amount of tread laid on the road -
rather than 2 x Pi x standing height. If that is that case, a soft
tyre would not rotate at a higher speed than an inflated one.
The article referenced in another post says "The rolling radius of
the tire becomes smaller in proportion to the rate of deflation and
therefore the wheel speed of the deflated tire increases."
Surely if the length of the tread is 1.5m (and if it's a steel belt
radial or similar so won't change with inflation/deflation),
travelling this distance causes the wheel to rotate once whether
fully inflated or running on the rim?

With lower pressure, the tread gaps will be able to close up a little,
which will change the 'tread length' more obviously than it will change
the 'rolling radius'. The article is claiming a 3mm /1% difference,
which seems plausible, but you would want to cover a long distance
before deciding the difference in rotation wasn't due to roundabouts.

Rather than guessing whether you've been driving in a straight line or
not, surely it makes sense to monitor the steering.

--
Mike Barnes

Mike Barnes wrote:

Rather than guessing whether you've been driving in a straight line or
not, surely it makes sense to monitor the steering.

Yes, or the lateral acceleration, if there was already a sensor
monitoring either of them. Otherwise use the existing ABS sensors and
some less-stupid software in the controller.

On 11 Sep 2008 19:27:43 GMT, Adrian wrote:

The key is _totally_ flat, rather than just soft.

Agreed no tyre will survive long if internal surafces are being forced
into contact even just briefly on bumps. That I would call "flat". Soft is
when there is still pressure in the tyre but it's not enough and the shape
is visibly different and the handling noticeably altered. This is with
normal tyres mind not a thick rubber band...

If a tyre picks up a puncture and goes flat when running the chances are
it will be killed but a slow leak where you loose just a couple of
psi/week should be picked up by visual observation/change in handling(*)
or if those don't occur 'cause rubber bands are fitted rather than proper
tyres you'll have to resort to actual pressure checks.

(*) Trouble is modern cars are very reliable, just feed them fuel and
drive. Take them to the garage to be serviced occasionally and get the MOT
if it's old enough to require one. Many drivers simply don't notice via
the handling or bother to look for a soft tyre. To me a normal profile
tyre that is 5 to 10psi down is very obvious.

--
Cheers
Dave.

"Mike G" wrote in message
...

"Brimstone" wrote in message
...
Roger Mills wrote:
Does anyone out there have any experience of wireless tyre pressure
monitoring devices - the sort which have special valves containing a
sensor, and a central display with LEDs and a bleeper and report
status?
Yesterday, I wrote off an otherwise perfectly good 225/45x17 tyre
because I had apparently been driving it flat for a while without
noticing.
In days of yore I could always tell by the seat of my pants if a tyre
was a bit flat. But many modern cars are grossly over-tyred, with
very wide low profile tyres which *look* flat when they're not, and
don't really *feel* any different when they are.

At £100 a throw, you don't have to write off too many tyres before a
monitoring system would be cheaper.

Any comments or recommendations?

How about manuall checking your tyre pressures weekly, at the same time
as you make all your other routine checks?

You do make routine checks don't you?

Unfortunately routine checks don't cover all eventualities.
Does anyone visually check all 4 tyres every time they use their car?

*waves*

Yeah I do. Old military habit. Pressures and tread depth is checked around
every 2,500 miles, more frequently for new tyres.

I can sympathise with the OP as I wrote off a 255x40x17 tyre in a similar
way. At low speeds, on a straight road, it's very difficult to detect a
flat low profile rear tyre.

It is. Fortunately, this car has the lowest profile tyre I've yet owned,
which is only a 215/55/16, so it still looks like a tyre.

In my case it was the n/s rear tyre. Fine in the morning. Jumped in and
drove about 300 yds straight up the road on my way home. Realised
something was not quite right, so stopped and found the flat tyre.
Changed it for the spare, but the damage was done. With the weight of the
car on the fold in the tyre, the carcass had started to delaminate.

The only consolation, if you can call it that, is that the tyre would have
been scrap anyway, as a the puncture which had caused it to deflate during
the day was an unrepairable one on the shoulder.

I checked and decided against the option of tyre monitors. Aftermarket
ones rely on wireless dust caps, which are too easily nicked. I just check
the tyres a bit more frequently than I did before.

....and are of course unproven in any application until you've had them for a
while, too.

--
The DervMan
www.dervman.com

DervMan wrote:
"Mike G" wrote in message
...

"Brimstone" wrote in message
...
Roger Mills wrote:
Does anyone out there have any experience of wireless tyre pressure
monitoring devices - the sort which have special valves containing
a sensor, and a central display with LEDs and a bleeper and report
status?
Yesterday, I wrote off an otherwise perfectly good 225/45x17 tyre
because I had apparently been driving it flat for a while without
noticing.
In days of yore I could always tell by the seat of my pants if a
tyre was a bit flat. But many modern cars are grossly over-tyred,
with very wide low profile tyres which *look* flat when they're
not, and don't really *feel* any different when they are.

At £100 a throw, you don't have to write off too many tyres before
a monitoring system would be cheaper.

Any comments or recommendations?

How about manuall checking your tyre pressures weekly, at the same
time as you make all your other routine checks?

You do make routine checks don't you?

Unfortunately routine checks don't cover all eventualities.
Does anyone visually check all 4 tyres every time they use their car?

*waves*

Yeah I do. Old military habit. Pressures and tread depth is checked
around every 2,500 miles, more frequently for new tyres.

I can sympathise with the OP as I wrote off a 255x40x17 tyre in a
similar way. At low speeds, on a straight road, it's very difficult
to detect a flat low profile rear tyre.

It is. Fortunately, this car has the lowest profile tyre I've yet
owned, which is only a 215/55/16, so it still looks like a tyre.

In my case it was the n/s rear tyre. Fine in the morning. Jumped in
and drove about 300 yds straight up the road on my way home. Realised
something was not quite right, so stopped and found the flat tyre.
Changed it for the spare, but the damage was done. With the weight
of the car on the fold in the tyre, the carcass had started to
delaminate. The only consolation, if you can call it that, is that the
tyre
would have been scrap anyway, as a the puncture which had caused it
to deflate during the day was an unrepairable one on the shoulder.

I checked and decided against the option of tyre monitors.
Aftermarket ones rely on wireless dust caps, which are too easily
nicked. I just check the tyres a bit more frequently than I did
before.

...and are of course unproven in any application until you've had
them for a while, too.

I fitted a set of those valve caps that show a red strip when the pressure
drops. They were just under £10 for the set and work a treat. When I first
got them I kept a check on them with a digital pressure guage - but I'm now
happy that they work accurately and a quick visual check when washing the
car is all that's needed. I've had them on for over a year now and they
haven't been nicked yet.

Ret.

On Sun, 02 Nov 2008 12:02:39 -0000, Ret. xxx wrote:

DervMan wrote:
"Mike G" wrote in message
...

"Brimstone" wrote in message
...
Roger Mills wrote:
Does anyone out there have any experience of wireless tyre pressure
monitoring devices - the sort which have special valves containing
a sensor, and a central display with LEDs and a bleeper and report
status?
Yesterday, I wrote off an otherwise perfectly good 225/45x17 tyre
because I had apparently been driving it flat for a while without
noticing.
In days of yore I could always tell by the seat of my pants if a
tyre was a bit flat. But many modern cars are grossly over-tyred,
with very wide low profile tyres which *look* flat when they're
not, and don't really *feel* any different when they are.

At £100 a throw, you don't have to write off too many tyres before
a monitoring system would be cheaper.

Any comments or recommendations?

How about manuall checking your tyre pressures weekly, at the same
time as you make all your other routine checks?

You do make routine checks don't you?

Unfortunately routine checks don't cover all eventualities.
Does anyone visually check all 4 tyres every time they use their car?

*waves*

Yeah I do. Old military habit. Pressures and tread depth is checked
around every 2,500 miles, more frequently for new tyres.

I can sympathise with the OP as I wrote off a 255x40x17 tyre in a
similar way. At low speeds, on a straight road, it's very difficult
to detect a flat low profile rear tyre.

It is. Fortunately, this car has the lowest profile tyre I've yet
owned, which is only a 215/55/16, so it still looks like a tyre.

In my case it was the n/s rear tyre. Fine in the morning. Jumped in
and drove about 300 yds straight up the road on my way home. Realised
something was not quite right, so stopped and found the flat tyre.
Changed it for the spare, but the damage was done. With the weight
of the car on the fold in the tyre, the carcass had started to
delaminate. The only consolation, if you can call it that, is that the
tyre
would have been scrap anyway, as a the puncture which had caused it
to deflate during the day was an unrepairable one on the shoulder.

I checked and decided against the option of tyre monitors.
Aftermarket ones rely on wireless dust caps, which are too easily
nicked. I just check the tyres a bit more frequently than I did
before.

...and are of course unproven in any application until you've had
them for a while, too.

I fitted a set of those valve caps that show a red strip when the pressure
drops. They were just under £10 for the set and work a treat. When I first
got them I kept a check on them with a digital pressure guage - but I'm now
happy that they work accurately and a quick visual check when washing the
car is all that's needed. I've had them on for over a year now and they
haven't been nicked yet.

Wouldn't work here - I have never washed a car. Why wash something which will get dirty next time you use it?

--
http://www.petersparrots.com http://www.insanevideoclips.com http://www.petersphotos.com

One day, a mom was cleaning her son's room and in the closet she found a bondage S&M magazine.
This was highly upsetting for her.
She hid the magazine until his father got home and showed it to him.
He looked at it and handed it back to her without a word.
She finally asked him, " Well what should we do about this?"
The dad looked at her and said, "Well I don't think you should spank him."