[malcolm]

I have run flat tyres on my car with metal valves, think they have something to do with the tyre monitor, i have been told you can't fit metal valve caps to them, can any one confirm if that’s true as i would like to change the black plastic ones.

Thanks

[F31-340i]

My wheels have the OEM metal caps. I would recommend not being tempted by any cheap ebay chrome caps - they'll likely corrode to the valve and can prove impossible to remove without revalving the wheel (happened on my Mini). Either go OEM metal, or stay plastic.

[doughboy]

Originally Posted by malcolm

I have run flat tyres on my car with metal valves, think they have something to do with the tyre monitor, i have been told you can't fit metal valve caps to them, can any one confirm if that’s true as i would like to change the black plastic ones.

Thanks

BS i'm afraid.

Tyre pressure monitor system (TPMS) uses ABS wheel speed sensors to detect low pressure tyre. Only US cars have pressure sensors in the wheel valve assembly.

You can fit whatever caps you like. The valves for RFTs are the same as for any normal wheel/tyre combo.

[Dr Dave]

Indeed, as DB says. You've been fed some pub-car-expert bullshit.

[ShereKhan]

Originally Posted by malcolm

I have run flat tyres on my car with metal valves, think they have something to do with the tyre monitor, i have been told you can't fit metal valve caps to them, can any one confirm if that’s true as i would like to change the black plastic ones.

Thanks

I drove around for a few months without caps. After I realised that Kwik Fit had threw them away when changing tyres. As Doughboy says the wheel speeds are monitored to work out if you have a flat tyre.

[SoCalTech]

If you have the sensors in the wheels (not sure which system is used in your part of the world...) then you are not supposed to use metal valve stem caps. It supposedly messes with the radio signal.

[R80TER]

Originally Posted by SoCalTech

If you have the sensors in the wheels (not sure which system is used in your part of the world...) then you are not supposed to use metal valve stem caps. It supposedly messes with the radio signal.

so the large amount of metal around the valve cap (ie the wheel!) doesn't??

[Dr Dave]

Well spotted R80!!!!!

[AlanQS]

The wheels aren't steel so it wouldn't interfere. In Britain, the tyre pressure monitor is based upon the ABS sensors so put any kind of cap you like on the valve. When new, both my original wheels and my 230s were supplied by BMW with metal caps.

A separate tyre monitoring system seems to be required by American regulations but some members on this side of the pond do appear to have non standard valves and it may be that certain models had the American system. I suspect Tone would be the guy to know.

[malcolm]

Thanks for the replys, i've posted a wee pic as the valves are differant from others i've seen, going to get a set of metal caps and see what happens.



PS off to give them a clean.

[I335]

I have OEM metal caps on my M6 reps with TPMS - works just fine. That said, the dealer told me that there's a possibility that they'll corrode and be hard to remove, but a year later they're still just fine - not seeing any corrosion or anything unusual at all. My car is in a climate-controlled garage day & night though so maybe that's the difference. I work from home so my car rarely sits outside for any lenght of time.

[doughboy]

Originally Posted by SoCalTech

If you have the sensors in the wheels (not sure which system is used in your part of the world...) then you are not supposed to use metal valve stem caps. It supposedly messes with the radio signal.

Only US have the pressure sensors. Evryone else uses ABS speed sensors.

But the valve stems are steel anyway (coated in rubber) as the thread is metal even on a rubber coated stem, and the valve mechanism is metal too.

Can't see why a metal cap would make any difference??

Malcolm:

They are strange looking valve stems..... not seen them before. Defo not factory fit (or Kwik fit either!!) You sure they're not imported wheels? from ebay or somewhere?

Are they what the US TPMS stems look like?

[SoCalTech]

Originally Posted by R80TER

so the large amount of metal around the valve cap (ie the wheel!) doesn't??

It's what I was taught when I went to BMW factory training. Personally, I've seen them with metal caps without issue, but according to BMW it can cause issues.

[SoYank]

Originally Posted by SoCalTech

It's what I was taught when I went to BMW factory training. Personally, I've seen them with metal caps without issue, but according to BMW it can cause issues.

Well, who's to argue with BMW factory training? It does seem extremely odd that a small piece of metal at the end of the valve stem could cause problems with the radio reception to or transmission from a device inside a metal wheel, BMW assertion notwithstanding.

However, my opinion is that the issue lies with the dissimilar metals involved causing galvanic corrosion thus making the valve covers difficult to remove or even, depending upon the metals involved, the destruction of the valve stem itself which is metal. When the caps are corroded on sufficiently, attempting to remove them may require enough force that the stem gets damaged and requires replacement.

BTW, Malcolm, your valve stems look the same as mine, albeit dirtier , and I have the TPMS which utilizes the in-the-wheel sensors.

[ed335d]

Originally Posted by doughboy

Only US have the pressure sensors. Evryone else uses ABS speed sensors.

But the valve stems are steel anyway (coated in rubber) as the thread is metal even on a rubber coated stem, and the valve mechanism is metal too.

Can't see why a metal cap would make any difference??

Malcolm:

They are strange looking valve stems..... not seen them before. Defo not factory fit (or Kwik fit either!!) You sure they're not imported wheels? from ebay or somewhere?

Are they what the US TPMS stems look like?

These are factory fit - they came on my 230's. They are a bit of a pain, as one snapped when I was putting air in, and you can only get them from BMW - had to have a rubber one to repair it and then replace it when I managed to get a matching one.

[malcolm]

I take it there factory fit as they were fitted to the car when i bought it, i take from what’s been said that they have nothing to do with the tyre monitor, i just have to watch the valve caps don't corrode to the valves as they may damage them, that should be ok as i check the tyre pressures once a week.

Thanks for the info.

[ed335d]

Originally Posted by malcolm

I take it there factory fit as they were fitted to the car when i bought it, i take from what’s been said that they have nothing to do with the tyre monitor, i just have to watch the valve caps don't corrode to the valves as they may damage them, that should be ok as i check the tyre pressures once a week.

Thanks for the info.

Nothing to do with the TPM at all!

[SoCalTech]

That definitely looks like a TPM sensor to me. Are you sure you do not have TPM instead of FTM? Look in the front of the front wheel well liners. There will be a transmitter bolted to the liner if you have TPM.

[doughboy]

Originally Posted by malcolm

I take it there factory fit as they were fitted to the car when i bought it, i take from what’s been said that they have nothing to do with the tyre monitor, i just have to watch the valve caps don't corrode to the valves as they may damage them, that should be ok as i check the tyre pressures once a week.

Thanks for the info.

Malcom, like i said........even 'rubber' stems have a metal portion inside to receive the screw in schrader valve. The metel body protrudes out of the rubber casing to expose the cap screw threads.

Thus the part you screw the cap on to (or where you attach the air line) is ALWAYS threaded metal on any type of car tyre valve, so the risk of corrosion is always there, but i have never experienced it.

Take a look and see on any car.

[ed335d]

Originally Posted by SoCalTech

That definitely looks like a TPM sensor to me. Are you sure you do not have TPM instead of FTM? Look in the front of the front wheel well liners. There will be a transmitter bolted to the liner if you have TPM.

Nope, it's just a metal valve:

http://www.realoem.com/bmw/showparts...78&hg=36&fg=15

These metal threaded part of these valves is a different composition to a normal rubber valve (which is typically brass in appearance). The threaded part of the metal valves does look like it corrodes a bit - so I wouldn't be surprised if a metal valve cap could bond with it.

[doughboy]

My oem metal valve caps are stainless steel anyhow, so hopefully corrosion free in all cases!

[LRS]

Give (Auto 4 Ltd) a call. You can buy a box of 50 of the OEM BMW silver/grey plastic caps for less than a fiver! Great if you keep getting them nicked.

No:232220 £3.77 (BOX OF 50) + VAT (Silver/Grey Plastic Valve Stem Caps)

These are the ones that came from the factory on my 230s.