Hi All,

I'm about to sell my 14' sailing dinghy to my sister and have just
checked it all out etc.

It has been standing in my dark / cool lockup (on chocks) for the last
8 years and although the tyre pressures were quite low they pumped
back up fine and look perfect (no cracking / crazing / discoloration
etc etc.

Now I guess I know the answer to the 'should I fit new tyres'
question, but these are very high quality Michelins (fitted because a
new cheaper brand tyre was failed) and have only done about 300 miles
(Lake district to London) ;-(

So, is this 'max 7 years' thing a function to how a tyre has been
stored (hot / cold, wet / dry) and if it has been exposed to the sun
etc?

Sister is only 30 miles away (and I'd go back roads and do have a
spare wheel) and the sailing club only 3 miles from her (where the
road trailer will probably just disappear in the long grass).

And it's not a 30' 3 tonne caravan (only 200kg gross) ;-(

All the best ..

T i m

"T i m" wrote in message
...
Hi All,

I'm about to sell my 14' sailing dinghy to my sister and have just
checked it all out etc.

It has been standing in my dark / cool lockup (on chocks) for the last
8 years and although the tyre pressures were quite low they pumped
back up fine and look perfect (no cracking / crazing / discoloration
etc etc.

Now I guess I know the answer to the 'should I fit new tyres'
question, but these are very high quality Michelins (fitted because a
new cheaper brand tyre was failed) and have only done about 300 miles
(Lake district to London) ;-(

So, is this 'max 7 years' thing a function to how a tyre has been
stored (hot / cold, wet / dry) and if it has been exposed to the sun
etc?

Sister is only 30 miles away (and I'd go back roads and do have a
spare wheel) and the sailing club only 3 miles from her (where the
road trailer will probably just disappear in the long grass).

And it's not a 30' 3 tonne caravan (only 200kg gross) ;-(

The tyre makers, trade association, or whoever came up with the "7 year"
idea are covering their backsides against the person who parks a trailer
in bright sun, lets the tyres go completely flat, and then loads it to
the rated load and runs it at the rated speed. It sounds as though
you'll be using them at a fraction of their rated load, (unless they're
those 8" glorified wheelbarrow tyres) and they will barely get warm on
the journey in question. Most people running classic and vintage cars
will happily use tyres 30 or 40 years old, and give them a good run at
close to their maximum load. I'd inflate them a bit over pressure,
check the tread and sidewalls carefully for any bumps or distortion, and
if they're OK drop them back to pressure and tow away.

If you act on this advice, I will indemnify you against all loss,
damage, or claims up to the amount you paid for this advice.


--
Kevin Poole
**Use current month and year to reply (e.g. )***

On Sun, 22 Apr 2007 18:38:55 +0100, Autolycus wrote:

I'd inflate them a bit over pressure, check the tread and sidewalls
carefully for any bumps or distortion, and if they're OK drop them back
to pressure and tow away.

I'd also under inflate and squish them to see if any cracks open up in the
side walls. One of my trailer tyres loks fine inflated but when it's a bit
soft the crack open up...

--
Cheers
Dave. pam is missing e-mail

On Sun, 22 Apr 2007 18:38:55 +0100, "Autolycus"
wrote:



So, is this 'max 7 years' thing a function to how a tyre has been
stored (hot / cold, wet / dry) and if it has been exposed to the sun
etc?

The tyre makers, trade association, or whoever came up with the "7 year"
idea are covering their backsides against the person who parks a trailer
in bright sun, lets the tyres go completely flat, and then loads it to
the rated load and runs it at the rated speed.

Understood.

It sounds as though
you'll be using them at a fraction of their rated load, (unless they're
those 8" glorified wheelbarrow tyres) and they will barely get warm on
the journey in question.

4.00 x 8 Michelin High Speed trailer tyres .. ;-)

Most people running classic and vintage cars
will happily use tyres 30 or 40 years old, and give them a good run at
close to their maximum load.

Oh, ok, and I assume they are sitting in the things (rather than just
trailing behind).

I'd inflate them a bit over pressure,
check the tread and sidewalls carefully for any bumps or distortion, and
if they're OK drop them back to pressure and tow away.

Ok, will do, thanks.

If you act on this advice, I will indemnify you against all loss,
damage, or claims up to the amount you paid for this advice.

It's a deal.;-)

All the best ..

T i m

On Sun, 22 Apr 2007 20:11:00 +0100 (BST), "Dave Liquorice"
wrote:

On Sun, 22 Apr 2007 18:38:55 +0100, Autolycus wrote:

I'd inflate them a bit over pressure, check the tread and sidewalls
carefully for any bumps or distortion, and if they're OK drop them back
to pressure and tow away.

I'd also under inflate and squish them to see if any cracks open up in the
side walls. One of my trailer tyres loks fine inflated but when it's a bit
soft the crack open up...

Ok, another good test thanks.

A thought though, just what percentage of the strength of a tyre
(especially the sidewall) is down to the rubber rather than the
'ply's'?

I mean the rubber 'inside' the fabric would tend to keep the air in
(these tyres are tubed in this case though) and the stuff on the
outside helps give the sidewall it's 'stiffness' and protect the ply
from abrasion etc?

I guess what I'm trying to ask here is is it possible that a crack (or
cracks) in the sidewall *might* not actually increase the risk of the
tyre deflating or delaminating etc?

I have a very old trailer (in itself very tidy) with equally old tyres
with lots of very fine cracks in the sidewall but it only gets used
for a very rare slow trip to the local dump etc (and wouldn't be
'noticed' unless inspected very closely). I probably first spotted the
issue 10 years ago but they seem to have survived?

All the best ..

T i m

p.s. I would very probably fit new tyres 'anyway' if they were on our
cars or motorbikes and especially if they were going to be used
regularly or at any speed / distance.

"T i m" wrote in message
...
snip

A thought though, just what percentage of the strength of a tyre
(especially the sidewall) is down to the rubber rather than the
'ply's'?

I mean the rubber 'inside' the fabric would tend to keep the air in
(these tyres are tubed in this case though) and the stuff on the
outside helps give the sidewall it's 'stiffness' and protect the ply
from abrasion etc?

I guess what I'm trying to ask here is is it possible that a crack (or
cracks) in the sidewall *might* not actually increase the risk of the
tyre deflating or delaminating etc?

AIUI, problems may arise when water reaches the reinforcement and rots /
rusts / is absorbed by it. This could result in it separating from the
rubber, and is one of the reasons you shouldn't repair a puncture just
by fitting an inner tube.

I have a very old trailer (in itself very tidy) with equally old tyres
with lots of very fine cracks in the sidewall but it only gets used
for a very rare slow trip to the local dump etc (and wouldn't be
'noticed' unless inspected very closely). I probably first spotted the
issue 10 years ago but they seem to have survived?

They do.

Many moons ago, my father complained to Pirelli about their new-fangled
Cinturatos cracking on his MG 1100. They told him it was because he
didn't drive fast enough to get them hot regularly, but then, without
admitting anything, gave him a nearly new set foc.


--
Kevin Poole
**Use current month and year to reply (e.g. )***

On Mon, 23 Apr 2007 16:22:58 +0100, "Autolycus"
wrote:

I guess what I'm trying to ask here is is it possible that a crack (or
cracks) in the sidewall *might* not actually increase the risk of the
tyre deflating or delaminating etc?

AIUI, problems may arise when water reaches the reinforcement and rots /
rusts / is absorbed by it. This could result in it separating from the
rubber, and is one of the reasons you shouldn't repair a puncture just
by fitting an inner tube.

Ah, good points ta. I *nearly* repaired the leaky rim on the kitcar by
fitting a tube but I'd rather fix the problem properly by stripping
the flaking paint off the rim. I just didn't get roundtuit, now I
have a damaged sidewall. ;-(

I have a very old trailer (in itself very tidy) with equally old tyres
with lots of very fine cracks in the sidewall but it only gets used
for a very rare slow trip to the local dump etc (and wouldn't be
'noticed' unless inspected very closely). I probably first spotted the
issue 10 years ago but they seem to have survived?

They do.

Many moons ago, my father complained to Pirelli about their new-fangled
Cinturatos cracking on his MG 1100. They told him it was because he
didn't drive fast enough to get them hot regularly, but then, without
admitting anything, gave him a nearly new set foc.

Hmmm, result indirectly then. ;-)

The rear Colways were showing signs of cracking where the tread joins
the sidewall and they changed them free .. including the fitting /
balancing .. and they were 7 years old! ;-)

All the best ..

T i m