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.

[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.

[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?

[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.

[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?

[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.

[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.

[Damian-k8d34]

There’s nobody letting the tyre down, it’s parked in our garage each night.

I’ve just got back from a 4 wheel alignment appointment as I thought that could be something to do with the issue and the garage showed me that they couldn’t attach the alignment wheel clamp to the drivers rear wheel as the the wheel arch was lower on this corner and there wasn’t enough space between the wheel and the arch to get the device clamped. They looked under the car in that corner but they couldn’t see anything wrong or why this corner would be slightly lower than the passenger rear side. Could this corner being slightly lower be a reason as to why I’m losing tyre pressure? Does anyone know about this corner being a problem on 3 series’?

[Damian-k8d34]

Dave. said:

Pics?

This is the wheel that’s losing pressure and they couldn’t get the alignment device attached. It’s roughly half an inch less between the wheel and the arch.

Edited by Damian-k8d34 on Wednesday 24th June 14:34

Edited by Damian-k8d34 on Wednesday 24th June 14:35

[Damian-k8d34]

Dave. said:

Pics?

[Damian-k8d34]

Oldandslow said:

What type of TPMS?

ABS based:
How are the shocks at the back? My GF's old boss used to get tyre pressure warning on a particular road because one of his wheels skipped about.

Actual transmitters:
Do they need reprogrammed if wheels moved around?
How old are they?

Sorry, I don’t know what TPMS is?

I believe the shocks are fine as nothing was mentioned on the MOT and I also had a major service at BMW 12 months ago and nothing was picked up.

If for some reason there’s extra weight on that corner or the whatever the reason is for that corner being half an inch lower, could that be putting extra pressure on that wheel which is causing air to leak from somewhere even if there’s nothing wrong with the tyre or wheel?

[Damian-k8d34]

kev b said:

Many BMWs are lower on the passenger side from the factory, it is said that they are made that way to compensate for the weight of the driver and they cannot be bothered to alter it for RHD cars.

Not sure whether to believe it, however my E36 and E46 were both like this.

As for the pressure drop then the wheel needs to go back in a water tank and be checked for bubbles, its not rocket surgery, I suspect tampering though.

Mines lower on the drivers side...

[Damian-k8d34]

Green1man said:

Are you regularly driving up a kerb or similar on that side? Sometimes the bead can be momentarily unseated and you lose a short blast of air. It’s happened to me a few times where one tyre is down low for some reason, pump it up and no further problems. A persistent and consistent issue would be a bit of a stretch here but I guess is possible.

No, I’m not driving up any curbs. The pressure will still drop if the car isn’t even being driven.

[Damian-k8d34]

Collectingbrass said:

You've got two things going on that I can see, the attitude / stance of the rear of the car and whatever is happening to the tyre in the OSR position.

Firstly, on the stance of the rear. It will be a broken spring the garage who checked haven't been able to see. I had exactly the same problem on an E36 that had passed two MOTs in my ownership without picking it up before I took it for a 4-wheel alignment where they couldn't clamp the gauge on the wheel - and that place didnt see it either. I thought the car's stance was normal because I had seen so many others like it. Later on, I had the suspension refreshed and that revealed the broken spring.

In terms of the pressure loss, you say it happens regardless of which wheel it is on that corner, so it must be something to do with the stance and geometry of the car at that corner. It could be that rear stance is changing the suspension geometry enough to do one or all of:
- open a hair line crack in the wheel (even the new one)
- break the bead enough to let enough air out

Take it to a decent independent specialist and get them to tear down that corner till they find what's wrong. There’s a list of specialists here on the BMW page https://www.pistonheads.com/gassing/topic.asp?h=0&...

Thanks for this, it’s very insightful. When you say spring, do you mean the big suspension spring? If it is indeed a broken spring as you mention, do you have a rough idea of how much that would cost to fix including garage labour? What did you have to end up paying? Thanks

Edited by Damian-k8d34 on Wednesday 24th June 17:35

[Damian-k8d34]

Collectingbrass said:

This was all done in 2017. The whole suspension refresh was £1400, a rear spring on its own was about £125 including labour & VAT, springs and dampers on both sides was about £400.

Thanks. I’m assuming that if I did have a damaged spring then all I’d need doing was having that replaced and none of the other stuff you mentioned that you had done?

[Damian-k8d34]

Matt_E_Mulsion said:

You've still not told us how you are measuring this 10psi pressure drop.

I did in an earlier post. I know what psi I fill it up to and when the dash light comes on I go to the garage to use their air machine and as soon as you attach it it reads the current psi.

[Damian-k8d34]

tapkaJohnD said:

Thank you, MB140! Learn something every day.

To the OP, if that applies to your car, then that, with your evidence of a lower ride on that side and that exchanging the wheel doesn't move the problem, points to a suspension, not a tyre/wheel problem.

Yes, given that the rear drivers side is lower and that’s the wheel I keep losing air from the wheel regardless of which wheel I put in there perhaps does point towards the spring/suspension being damage and causing all of this. I still don’t understand though how a damaged spring/suspension would cause air to escape from a wheel?

Just found this old thread: https://www.pistonheads.com/gassing/topic.asp?h=0&...

Edited by tapkaJohnD on Thursday 25th June 10:30

[Damian-k8d34]

Matt_E_Mulsion said:

So which wheel/tyre combo is currently on the driver's side rear and losing pressure? If its the old wheel and tyre that used to be on the passenger side maybe that one is leaking around the bead too and suffering the same corrosion problems that the other wheel had. Why not have that wheel taken off and dunked in a tank of water to see if it is bubbling too?

I’ve got replacement alloy on the drivers rear as there was no point having a different alloy on there once I discovered the problem didn’t follow the alloy but instead remained on the drivers rear. Yes, I think I’ll have to get this wheel dipped but given the problem doesn’t follow the alloy I don’t think it’s the alloy leaking. I’m leaning towards the problem being the spring (as the car is lower this corner) but I don’t understand how a potentially damaged spring can cause air to leak.

[Damian-k8d34]

I took it to a garage this morning and they took the wheel off and inspected the alloy which they said they couldn’t see any cracks and then they dipped the wheel in water and there were no bubbles.

I can buy a tyre pressure gauge but the fact I have had to fill this wheel with air on at least 5 occasions tells me that the air pressure machine at the garage and the sensor on my car are reading correct as I have topped up over 50psi combined on this tyre on top of already what’s still remaining in the tyre and therefore it would have bust if the correct air was in fact still in the tyre as a result of a faulty sensor or air pressure machine at the garage.

I think the lower rear corner is somehow adding pressure to whichever wheel I put on the drivers rear and is causing air to leak (forced out) of the tyre but when the wheel is off air is not escaping because it’s not under the pressure.

Edited by Damian-k8d34 on Friday 26th June 16:15

[Damian-k8d34]

This is not a wind up. I have much better things to do with my time than waste it on here discussing a car issue. I came on here for advice as I was at a loss and over £500 down trying to fix it. As I mentioned, there was no bubbles appearing this morning when the tyre was dipped. I am also sure nobody is letting my tyres down.
I think everything has been exhausted and I won’t take up anymore of people’s time. Thank you to those who tried to help. If I end up discovering the issue I will post back on here.