Tyre Losing Pressure - Tried Everything - Help!

[Damian-k8d34]

Hi everyone, I have a 2008 BMW 3 Series Convertible and my rear drivers side tyre keeps losing about 10psi a month. I have tried everything to resolve this. I have put on a new run flat tyre and changed the valve stem which didn’t fix the problem, and then I even bought a new alloy in case the old one was cracked but still I keep losing 10psi a month.
Can anyone suggest why this is happening given that I have tried all I can think of and yet still it’s occurring? Thanks in advance.

[Dogwatch]

Try swapping with another wheel and see if the problem persists? If so it may be due to driving over a kerb or some other obstacle.

[longblackcoat]

Could be a cracked rim or possibly corrosion on the inside of the wheel causing a less-than-perfect seal

[Damian-k8d34]

Sorry, I should have also mentioned that I did swap the wheels and the problem still occurred on the drivers rear which means it’s not the alloy or tyre.

[Oldandslow]

So. If I'm reading this right it still leaks in that position even though it's a different tyre, valve and alloy?

Either you're very unlucky or the victim of a prankster.

How do you know the pressure is dropping? Is it TPMS or are you verifying with a gauge? If TPMS what type?

[TheBALDpuma]

Well if you've changed the wheels and the tyre then either...

a) You're really, really unlucky

b) This is some weird made up story

[Damian-k8d34]

Correct, I have swapped the wheels and 10psi a month is still leaking From the rear drivers wheel.
The red exclamation mark comes up on my dash warning me of low pressure and when I go to the petrol station is always the drivers rear which has gone down. This isn’t a wind up so any help would be really appreciated. I’m no mechanic but if I’ve ruled out the leak coming from the wheel so how else can air leak?

[xjay1337]

Damian-k8d34 said:

Correct, I have swapped the wheels and 10psi a month is still leaking From the rear drivers wheel.
The red exclamation mark comes up on my dash warning me of low pressure and when I go to the petrol station is always the drivers rear which has gone down. This isn’t a wind up so any help would be really appreciated. I’m no mechanic but if I’ve ruled out the leak coming from the wheel so how else can air leak?

It can't.

Tyre either leaks from

1) the valve
2) the bead of the tyre (usually due to corrosion on the alloy)
3) the tyre itself (puncture)
4) alloy crack


I don't believe it at all. Have you submerged the alloy in a bath?
I suspect someone is pranking you or this story is made up

[take-good-care-of-the-forest-dewey]

xjay1337 said:

It can't.

Tyre either leaks from

1) the valve
2) the bead of the tyre (usually due to corrosion on the alloy)
3) the tyre itself (puncture)
4) alloy crack


I don't believe it at all. Have you submerged the alloy in a bath?
I suspect someone is pranking you or this story is made up

It sort of can... But only once. Pressure measured and air fill done hot and the cold.

[Damian-k8d34]

After I changed the tyre and the valve and the problem continued I then had the garage dip the alloy and there was an ever so slight leak which is why I bought a new alloy but even now with the new alloy, new tyre and new valve the problem still happened. I then swapped the wheels and the problem still happens on the drivers rear This isn’t made up or someone else’s story, it’s happening to me and it’s 100% true.

[xjay1337]

take-good-care-of-the-forest-dewey said:

It sort of can... But only once. Pressure measured and air fill done hot and the cold.

That's not a leak though . It's natural pressure variations due to air density........

[kambites]

Either you're parking somewhere which is severely stressing that tyre, or (more likely) the new wheel is shot too.

[Damian-k8d34]

I’m not parking anywhere that would stress the wheel and it can’t be the wheel anyway as I’ve swapped the wheels and the problem isn’t following the wheel but instead the problem remains on the rear drivers side regardless of what wheel I put in there. I can only think it must be something to do with what the wheel attaches to but I’m not mechanical and I don’t know how that would cause air to leak?

[Matt_E_Mulsion]

How are you measuring this 10psi loss?

[Damian-k8d34]

Matt_E_Mulsion said:

How are you measuring this 10psi loss?

Because I know what I fill the tyre up to and then once I get the warning light on the dash and go to the petrol station to refill it comes up on the machine what the current psi is as you begin to put air back in. It’s not always dead on 10psi lost but in that region and enough loss to activate the warning dash light after about 4 weeks.

[Rowe]

Damian-k8d34 said:

I then swapped the wheels and the problem still happens on the drivers rear

so regardless of what wheel/tyre is fitted to the drivers rear, it leaks?

this site might be useful: https://www.bidvine.com/paranormal-investigation/n...

[Damian-k8d34]

Rowe said:

so regardless of what wheel/tyre is fitted to the drivers rear, it leaks?

this site might be useful: https://www.bidvine.com/paranormal-investigation/n...

Yes, that is correct.
There’s no need to take the mick. This is a genuine issue I’ve got and I’ve spent over £500 trying to resolve it and I’m still no better off than when I first started.
I was hoping this was something that was know on 3 series’ with run flats or a more mechanically minded person who could think of another cause for this. There has to be something up as it’s happening.

[Rowe]

the only other variable you haven't addressed is the car itself.

have you tried replacing that?

[randlemarcus]

Being kind, and avoiding all mention of ghosts

Up the thread, there is a fairly exhaustive list of reasons a tyre loses pressure.

I would suggest you get a tyre pressure measuring thingy off Amazon. Doesn't need to be expensive, one of the little pen ones would do. Measure the pressure every single time you drive the car for a couple of weeks. Multiple times a day if necessary. Note the pressures shown down.

At the end of the couple of weeks, have a look and see if you have a slow leak, or a fast one, that is losing precisely 10PSI. If the former, get you friendly tyre place to dip the new wheel. If bubbly, bad new alloy, send back for replacement.

If its the latter, get a webcam on the drivers wheel while you aren't there, and catch the next door neighbour letting the tyre down.

Forget ideas about the wheel attaching to the car, thats a red herring.

[Matt_E_Mulsion]

Every conceivable part has been replaced that could be the issue from what you've said, and the 'problem' appears to be with whichever wheel you fit to that corner. It just doesn't make logical sense.