Tyres "perishing"

50Twuncle

Ultrasonic wrote: »

As far as never putting air in goes, even tyres that are perfectly sealed so that no air ever leaks out still need extra air putting in during winter, as otherwise the pressures will be low due to lower ambient temperatures. If pressure checks haven't shown this the pressure gauge is broken.

So - do you also release some air in spring ?
If not - and there is no leak (as in my case) - surely your tyres will eventually explode through over-inflation ?

photome

50Twuncle wrote: »

So - do you also release some air in spring ?
If not - and there is no leak (as in my case) - surely your tyres will eventually explode through over-inflation ?

I know where you are coming from but that is really funny.

Any idea what pressure is needed before a tyre explodes?

Crabman

50Twuncle wrote: »

So - do you also release some air in spring ?
If not - and there is no leak (as in my case) - surely your tyres will eventually explode through over-inflation ?

Air escapes through the linings of the tyre itself as well as small imperfections in the valve seal and between the tyre and wheel rim.

Think about a party balloon - no matter how tight you tie the knot in the end, it will deflate over time.

photome

Crabman wrote: »

Air escapes through the linings of the tyre itself as well as small imperfections in the valve seal and between the tyre and wheel rim.

Think about a party balloon - no matter how tight you tie the knot in the end, it will deflate over time.

Don't think that is always true, I have had tyres like the OP that never lose any pressure, on the flip side I have had tyres that need topping up constantly due to the issues you highlight.

Don't think you could ever properly seal a balloon with a "knot"

Crabman

photome wrote: »

Don't think that is always true, I have had tyres like the OP that never lose any pressure, on the flip side I have had tyres that need topping up constantly due to the issues you highlight.

Don't think you could ever properly seal a balloon with a "knot"

They would have lost some pressure, perhaps if the valve and rim seals were good the loss would have been very low so not detectable. Detection would depend on the accuracy of the gauge being used to test the pressure.

photome

Crabman wrote: »

They would have lost some pressure, perhaps if the valve and rim seals were good the loss would have been very low so not detectable. Detection would depend on the accuracy of the gauge being used to test the pressure.

If the same gauge is used all the time (as mine is) I think I can say that no pressure has been lost

50Twuncle

Crabman wrote: »

Air escapes through the linings of the tyre itself as well as small imperfections in the valve seal and between the tyre and wheel rim.

Think about a party balloon - no matter how tight you tie the knot in the end, it will deflate over time.

A balloon loses pressure through diffusion of molecules through a semipermeable membrane from a place of higher concentration to a place of lower concentration until the concentration on both sides is equal.
This is a similar process to Osmosis - but as you are aware - Osmosis is only relevant in liquids
It has nothing to do with the knot......

50Twuncle

Crabman wrote: »

They would have lost some pressure, perhaps if the valve and rim seals were good the loss would have been very low so not detectable. Detection would depend on the accuracy of the gauge being used to test the pressure.

Maybe only detectable using laboratory standard gauges - which most of us do not possess ......
Don't forget that we are talking about first fit tyres on brand new rims - which will be airtight !!

GolfBravo

50Twuncle wrote: »

So - do you also release some air in spring ?
If not - and there is no leak (as in my case) - surely your tyres will eventually explode through over-inflation ?

For every 10ºC drop in ambient temperature, on average, you lose 1psi of tyre pressure. So in winter you have to pay particular attention to tyre pressures.

Overinflation: tyres have their max pressure written on the sidewall (usually over 50psi), and by law they are required to withstand that pressure under maximum allowed load (when brand new) - see tyre load index.

So it would take some serious overinflation and abuse for the tyre to explode.

50Twuncle

GolfBravo wrote: »

For every 10ºC drop in ambient temperature, on average, you lose 1psi of tyre pressure. So in winter you have to pay particular attention to tyre pressures.

Overinflation: tyres have their max pressure written on the sidewall (usually over 50psi), and by law they are required to withstand that pressure under maximum allowed load (when brand new) - see tyre load index.

So it would take some serious overinflation and abuse for the tyre to explode.

Or a fault (as appears the situation in my case).....