|
Hi - any thoughts on a fix for old alloys where the tyre pressure drops over a period of a few months - would one of those emergency repair cans of goo help or would that just make matters worse. Of course checking pressures and inflating is the normal 'fix' at the moment...
|
Very often it is not the alloy that is porous, but corrosion on the rim where the bead fits. Dunk the whole wheel under water and see where it is coming from.
A tyre place should be used to taking a tyre off, cleaning the wheel rim and refitting the tyre - I think they charged me £20 to do all five wheels a couple of years ago.
|
How old is it/them.Old tyres can leak as well?
--
Steve
|
|
|
Very often it is not the alloy that is porous, but corrosion on the rim where the bead fits.
Or around the valve ....
|
According to Bibendum (Mr Michelin) rubber is porous so air is lost through all tyres. (In my experience, pressure loss is greater the more the car is driven between checks).
If the leakage can only be detected over a period of months then by trying to prevent/reduce it you may be flogging a dead horse.
--
L\'escargot by name, but not by nature.
|
I second the valve theory.
The factory fit metal stem valves on my Mondeo alloys were to blame for all of my tyres losing pressure.
No such problem since I had them all replaced with standard rubber ones.
Yes they still lose the odd pound here and there over a period of months, but nothing like the few pounds a week they previously lost.
PP
|
Apparently filling tyes up with Nitrogen is all the rage in the US - something about the bigger molecules not leaking out like air does, and the tyre runs cooler.
I'm sure I read somewhere that ATS is trying it out.
|
something about the bigger molecules not leaking out like air does...
Yep.
www.honestjohn.co.uk/forum/post/index.htm?v=e&t=15...9
|
|
DD, what are these 'bigger molecules'? Air is 80% nitrogen anyway. Most of the rest is oxygen, which is about the same size. More snake oil perhaps? Though I believe bubble-wrap is filled with nitrogen (or is it CO²?).
|
Andrew,
Having just googled,
I think it's something to do with the oxygen in compressed air that is generally used to inflate tyres. Aparantly oxygen permeates three times faster than the nitrogen though a rubber tyre.
snipurl.com/dpzn
Don't shoot me, I'm just the messenger ;o)
|
|
|
|
|
I am (was) a chemist, not a metallurgist, but I can't believe anything happening to an aluminium alloy wheel to make it leak air through the metal, except perhaps microcracking (which would be pretty serious for other reasons?). My experience of alloy wheels is that the tyre/bead seal fails due to corrosion, and it used to happen commonly after a few years from new, at least on Pug 205GTi wheels. Things seem to be better now, as my 306 alloys are about 6 years old and seem to hold pressure as well as any steel wheel.
As has been said, the valve is another point to check. And tyres are thought to start surface cracking after 5 years anyway, aren't they?
|
|
|
![2019 Citroen C3 Aircross 1.2 PureTech 110 Feel 5dr [6 speed]](http://images.honestjohn.co.uk/imagecache/url/crop/90x60/https/cdn.uk.prod.group-mobility-trader.com/images/cas/2946deb5a2a25970424cab497bdb0c0d/4e9d76dcdfde708e9768e00be64da882.jpg)
