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[Markie]

Wifes old vectra is getting prepped for sale now she has the Omega ( I`ve changed brake lining sensors, oil and filter, temperature sensor and fixed door stays)

Its had an issue for 4 weeks whereby the front offside tyre goes down substantially and needed inflated every morning.

Ive removed it and cant see any sign of damage or a puncture anywhere and despatched wifey to budget to get it repaired.

They say ( like me) they cant find any hole, they say the valves are fine and they have inflated it again. They left it overnight in the bath and this morning its still inflated - i have the tyre back and its still indeed inflated..

So what is wrong with the tyre.....they say the weight of the car is deflating it....

[Jimbob]

Maybe the tyre is not sitting perfectly against the alloy, did you get them to reseal the tyre?

[Big Rod]

I had something similar where it turned out that although there was no evidence of corrossion around the rim, it turned out that some of the paint had come away from the metal itself right where the tyre meets the rim and the air was escaping that way. The paint was still in place, but the air was getting out under it!! In the end I resorted to some tyreweld.

You'll probably find that it woun't deflate as badly if you used the car regularly.

[Dazzler]

Yes, get the tyre sealed to the rim, then all should be dandy

[familyman]

Here is an intresting question. If you pump a tyre to say 2.1 bar off the car then fit it to the car the pressure inside with the weight of the car on the tyre remains at 2.1 bar??? Any scientists out there explain the theory behind this?

[Tafty]

Here is an intresting question. If you pump a tyre to say 2.1 bar off the car then fit it to the car the pressure inside with the weight of the car on the tyre remains at 2.1 bar??? Any scientists out there explain the theory behind this?

It's still the same volume of space inside the tyre - it's just shaped differently with the weight of the car - so no change to the pressure inside. So if the tyre was to be put on an articulated lorry the tyre would obviously flatten to the floor causing restrictions in space and therfore reducing the volume of space available inside the tyre - so increasing the pressure and most likely bursting it, also without the lorry and back on a normal car then it needs the air to heat up (expanding the volume of the air) so reducing the space and therefore increasing the pressure - vice versa on very cold tyres. 8-)

[STMO123]

Here is an intresting question. If you pump a tyre to say 2.1 bar off the car then fit it to the car the pressure inside with the weight of the car on the tyre remains at 2.1 bar??? Any scientists out there explain the theory behind this?

It's still the same volume of space inside the tyre - it's just shaped differently with the weight of the car - so no change to the pressure inside. So if the tyre was to be put on an articulated lorry the tyre would obviously flatten to the floor causing restrictions in space and therfore reducing the volume of space available inside the tyre - so increasing the pressure and most likely bursting it, also without the lorry and back on a normal car then it needs the air to heat up (expanding the volume of the air) so reducing the space and therefore increasing the pressure - vice versa on very cold tyres. 8-)

Have you just made that up Lee?

[familyman]

Here is an intresting question. If you pump a tyre to say 2.1 bar off the car then fit it to the car the pressure inside with the weight of the car on the tyre remains at 2.1 bar??? Any scientists out there explain the theory behind this?

It's still the same volume of space inside the tyre - it's just shaped differently with the weight of the car - so no change to the pressure inside. So if the tyre was to be put on an articulated lorry the tyre would obviously flatten to the floor causing restrictions in space and therfore reducing the volume of space available inside the tyre - so increasing the pressure and most likely bursting it, also without the lorry and back on a normal car then it needs the air to heat up (expanding the volume of the air) so reducing the space and therefore increasing the pressure - vice versa on very cold tyres. 8-)

Have you just made that up Lee?

 :oThat sounds almost convincing

[bob.dent]

I had this problem while I was in Devon last week Mark. No puncture or leaking valve - turned out to be air leaking from the rim and needed re-sealing. Had it done by National Tyres in Barnstaple at no charge

[Markie]

i`ll pick up some tyre weld then and give it a shot....dont want to replace the tyre for the buyer...

[Danny]

a mate of mine had this problem, he found the rim itself was cracked

[Tafty]

Here is an intresting question. If you pump a tyre to say 2.1 bar off the car then fit it to the car the pressure inside with the weight of the car on the tyre remains at 2.1 bar??? Any scientists out there explain the theory behind this?

It's still the same volume of space inside the tyre - it's just shaped differently with the weight of the car - so no change to the pressure inside. So if the tyre was to be put on an articulated lorry the tyre would obviously flatten to the floor causing restrictions in space and therfore reducing the volume of space available inside the tyre - so increasing the pressure and most likely bursting it, also without the lorry and back on a normal car then it needs the air to heat up (expanding the volume of the air) so reducing the space and therefore increasing the pressure - vice versa on very cold tyres. 8-)

Have you just made that up Lee?

 :oThat sounds almost convincing

Nearly convinced myself - was getting worried then

[megaomega123]

Agreed, leaking rims. I was also told that the wet look tyre spray can cause this. Not sure if it is true.

[nemesis_v6]

i have to agree about the rims if you can do it your self take the tyre off and give the inner lip a good scrup with wire bruss to see if any crap comes off then reseal it worked for me

[x25xe]

Also, alloy wheels can go porous.  Two of them on my Cav are porous at present - it is getting a real pain having to visit the garage to pump them up every two weeks.