[Zen_Driver]

Hi, I had an issue on my 325i with one of my rear tyres continually losing pressure over a period of a few days. I had to change the rear tyres anyway recently to get through the MOT but the problem hasn't gone away with the nice new Hankooks I had fitted. Am I looking at having to replace the rims now?? What could be going wrong? Any pointers appreciated, thanks!

[jacbo]

spray some soapy water right on the edge of the rim where it seals the tyre, see if it starts bubbling around the edge somewhere. I found on 2 of my rims that they were all crusty on the inside lip so would cause the tyre to not seal perfectly. This happened to a new tyre as well like yourself.

If that's the case, pop over to your local tyre shop and they'll grind away any corrosion on the inside of the rim and reseat it.

Worst case you have a crack in the rim somewhere. Which can be repaired depending on damage

[Zen_Driver]

Great, thanks for the tip! Will give that a go and hopefully the guys who fitted the new ones don't sting me!

Had two rather large bills recently (£1800 total) which has been getting me some 'looks' from the Mrs 😆

[Emilime75]

Did they replace the valve stems/seals when the new tires went on? Spray those with soapy water, as well.

[jacbo]

Originally Posted by Zen_Driver

Great, thanks for the tip! Will give that a go and hopefully the guys who fitted the new ones don't sting me!

Had two rather large bills recently (£1800 total) which has been getting me some 'looks' from the Mrs 😆

I went back to the shop i had the new tyres fitted and they did the rim cleanup and reseating free of charge so fingers crossed for you haha

[Hxm99]

Originally Posted by Zen_Driver

Hi, I had an issue on my 325i with one of my rear tyres continually losing pressure over a period of a few days. I had to change the rear tyres anyway recently to get through the MOT but the problem hasn't gone away with the nice new Hankooks I had fitted. Am I looking at having to replace the rims now?? What could be going wrong? Any pointers appreciated, thanks!

BMW rims are known to crack cos of the run-flat tyre - aluminium rim setup. Inspect the wheel for any cracks, even if small/hairline, it will cause loss of tyre pressure

[RajB]

Originally Posted by jacbo

I went back to the shop i had the new tyres fitted and they did the rim cleanup and reseating free of charge so fingers crossed for you haha

Hopefully that will have sorted it as is the most likely issue as they should have changed the valves as standard practice. The only thing would be a potential crack in the wheel but to cause air loss it would be noticeable.

[jwilalex]

This might sound daft but don't discount the valve cap either. I had a plastic set originally and one of them caused the valve to leak - god knows how but the garage showed me the wheel in a tub of water while I was doing some investigation and with that cap on sure enough.....bubbles and without air tight as it should be. They all got swapped out for tidy metal caps and been alright since.

[RajB]

Originally Posted by jwilalex

This might sound daft but don't discount the valve cap either. I had a plastic set originally and one of them caused the valve to leak - god knows how but the garage showed me the wheel in a tub of water while I was doing some investigation and with that cap on sure enough.....bubbles and without air tight as it should be. They all got swapped out for tidy metal caps and been alright since.

Ah I think that is more due to the pin screw in the centre of the valve not being done up properly so the cap pushes on the pin and releases air slowly. I did have that once and once screwed in properly it was fine.

[Emilime75]

Originally Posted by RajB

... they should have changed the valves as standard practice...

Not necessarily if the car has TPMS sensors, as those valve stems are part of the sensor. To service them the shop would need to unscrew them from the wheel, replace an inner o-ring and the sealing nut that holds them in place.
Assuming you guys have these, I know some markets don't. I'm in the U.S. and we do, however, in Canada, they are still not mandatory.

[RajB]

Originally Posted by Emilime75

Not necessarily if the car has TPMS sensors, as those valve stems are part of the sensor. To service them the shop would need to unscrew them from the wheel, replace an inner o-ring and the sealing nut that holds them in place.
Assuming you guys have these, I know some markets don't. I'm in the U.S. and we do, however, in Canada, they are still not mandatory.

Yes it TMPS sensors then agreed they wouldn't swap them out but the assumption was they are standard rubber valves and not TPMS sensors.
Ours vary from model to model and year to year unfortunately.