Metal tyre valve stems on new BMWs
Discussion
I was in a MINI dealership recently and noticed that all of the new cars seemed to have metal valve stems screwed into their wheels rather than the old rubber sort. From another thread on here, it seems that BMWs have recently made the same change (maybe MY 2014 or 2015?).
Is this to accommodate pressure sensors? As in have they now now got actual pressure sensors rather than using wheel speed via the ABS sensors?
If so, is there now a battery in each wheel to be replaced when it dies, or are they passive? Also how does this work when tyres are replaced? Previously tyre fitters would just rip out and replace the rubber valve stem, but these look like they've got plenty of potential to corrode themselves solidly into the wheel given a few salty winters...
Is this to accommodate pressure sensors? As in have they now now got actual pressure sensors rather than using wheel speed via the ABS sensors?
If so, is there now a battery in each wheel to be replaced when it dies, or are they passive? Also how does this work when tyres are replaced? Previously tyre fitters would just rip out and replace the rubber valve stem, but these look like they've got plenty of potential to corrode themselves solidly into the wheel given a few salty winters...
You can't replace the batteries but you can save a lot over OE by fitting aftermarket programmable valves. The quality is very good (see Autogem, i-sensor) and they are pretty easy to fit.
You need to programme the aftermarket valves to mimic the originals which can be done by scanning if the originals are still operative or by getting the actual valve, reading it's code and then scanning it into the new valve. There are quite a few tyre dealers able to supply, programme and fit the valves.
I changed those in my 911 myself but got a local dealer to supply the valves. He programmed three that were still working by scanning them in place. I had to remove the fourth to enable him to get the serial code. I then fitted the new valves myself.
You don't need to remove the tyre, break the bead and depress it near the valve and you'll have plenty of space to change.
Corrosion's not that big an issue unless you fit metal dust caps which tend to corrode themselves to the stem and break it off when you try to remove. Always use plastic dust caps!
There is also a small toolkit with a couple of special tools and a mini torque wrench for fitting the valves. It's important not to overtighten and the torque figures are very low, so worth getting.
I was quoted over £900 by the local Porsche dealer for new valves. It cost me about £325, including the toolkit, to do it myself.
You need to programme the aftermarket valves to mimic the originals which can be done by scanning if the originals are still operative or by getting the actual valve, reading it's code and then scanning it into the new valve. There are quite a few tyre dealers able to supply, programme and fit the valves.
I changed those in my 911 myself but got a local dealer to supply the valves. He programmed three that were still working by scanning them in place. I had to remove the fourth to enable him to get the serial code. I then fitted the new valves myself.
You don't need to remove the tyre, break the bead and depress it near the valve and you'll have plenty of space to change.
Corrosion's not that big an issue unless you fit metal dust caps which tend to corrode themselves to the stem and break it off when you try to remove. Always use plastic dust caps!
There is also a small toolkit with a couple of special tools and a mini torque wrench for fitting the valves. It's important not to overtighten and the torque figures are very low, so worth getting.
I was quoted over £900 by the local Porsche dealer for new valves. It cost me about £325, including the toolkit, to do it myself.
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