Tyre valve seal

[Mick787]

Just something to be aware of.

I recently, (6 months ago), I had a couple of tyres fitted to the rear axle of the car by Costco. The first set since the car was bought with the tyres fitted from new. Over the last couple of months the warning message came up that pressure had dropped on one of the rims that had a new tyre fitted on it. I couldn't see any nail/screw, so I assumed it may be a bit of rim leak after the same rim/tyre was loosing 4lbs pressure over 2 days.

I took the car back to Costco and they guys were superb. It turned out it was the rubber seal on the tyre valve that has perished. They fitted a new valve and advised that if air is used to inflate the tyre, that could well be the cause. They said they use nitrogen to pressurise the tyres because it does not create moisture and could not contribute to a similar failure.

As these valves aren't cheap, when the car goes into the dealership in the next couple of months we'll see what they have to say. The car is not yet 3 years old and I'm surprised the valve seal has failed after such a short time by way of perishing. I wonder if this has cropped up before with any owners.

 

[jadnashuanh]

When changing tires where the wheel has TPMS, industry guidelines call for replacing the seal. Depending on the age and battery status of the TPMS, it may be a good time to also swap in a new TPMS.

On any regular wheels without TPMS, they call for replacing the valve stem whenever changing the tire.

I think it's item #11 here https://www.realoem.com/bmw/enUS/showparts?id=1Z63-USA-06-2016-I01-BMW_i-i3_94Ah&diagId=36_1906

 

[Mick787]

An interesting reply jadnashuanh, thank you. When I am next in Costco, I will mention your information to their tyre bay staff. I will let them research if the UK/Europe has the same standards as the USA.

I know it is normal practise to replace a standard valve when fitting a new tyre. Even more cost implications for the owners of a relatively new car if it is a worldwide standard!

 

[jadnashuanh]

Cars have had TPMS for many years now, and at least in the USA, accepted practice is to replace the seal when changing a tire.

It can help if you add an area/country to your ID so country specific things can be better directed to your answers/inquiries.

I guess a clue was how you spelled tire/tyre...missed it.

 

[Mick787]

Further to your comment, I wonder what the life expectancy of the tyre valve is.
I assume the valve contains a battery, if so, surely it must have a life span? Does anyone know what happens when the battery starts to fail, what message can the owner expect to see on the car's display?

 

[jadnashuanh]

The TPMS is two parts, the valve, and the sensor. You can replace the valve stem when needed and reinstall it on the old sensor.

The TPMS goes to sleep when you stop. While you're driving, it broadcasts once per revolution (I think). So, it sort of depends on how much you drive. Most will last at least 5-years or so. After that, it's hard to say. There are test tools that can activate the sensors and report the battery status, its ID, and the tire pressure. Since the test tool gets the battery status, I'm assuming the vehicle does as well. From what I've seen, when that happens, the car displays TPMS failure. Internally, it knows which one(s) are bad, but it doesn't display that. On the two BMWs I own, my older one says failure, and then won't show the status for any of them (which I think is dumb!), so you don't know which one it is. That info is probably available with a BMW OBD-II reader, though, or their diagnostic computer.

Each TPMS has an embedded ID code, sort of like an ethernet adapter, so once the car learns which one is where on the car, it can report data fairly quickly once you start moving. During a reset, it listens for each report and since it doesn't know where they are, and they could be trying to talk at the same time, it can take awhile. Then, it has to figure out where they're located. I think it does that by trying to figure out which tire is rotating at different rates as you go around curves, otherwise, they'd all be going the same rate, and the reports would all occur at the same intervals. The i3 does not have multiple TPMS receivers...there's' one, so it has to do some calculating to figure out which one is which and where they are located.

 

[Mick787]

Very interesting. The guys at Costco had a tool they used, (it was obviously the item you were talking about), when asked what they were doing pointing this at the car, they said they're checking the TPMS sensor was talking to the car before they did the tyre change and they did it again afterwards, obviously to negate any allegation they had damaged the system. They were saying the tool cost them over £1000 but it was something they had to use. Long gone are the days of rubber valves and checking tyre pressures with a pencil gauge eh! I recall, back in the 70's they used to sell a tyre valve cap for rubber valves which was green, when the pressure dropped a couple of lbs, it turned orange.

Its just a shame that a simple rubber seal worth a few pence can fail so soon and result in a £40 repair, (plus labour) at a BMW dealership.

The idea of a monitoring system may be seen as progress, but it's yet another thing to go wrong and takes away the responsibility of the driver to do basic checks and ensure the car is safe. Yep, I'm a dinosaur! Mind you, I quite often see cars being driven on the road with tyres that are obviously well under pressure and in some cases..... flat. So there is a case to have these systems because many car drivers today won't know how to use a tyre pressure gauge!

 

[Timjohn]

What about the tire repair kit that BMW supplies with the i3? Repairing a flat with this system requires you to fill the tire with a sealant fluid and then let it seal the puncture. I really don't like this system. Doesn't this damage the TPMS sensors?

 

[jadnashuanh]

I was able to buy a TPMS tester on sale for about 100 pounds. I have two BMWs and each has two sets of tires. I figured it was cheap way to test the things. I can't see it costing anywhere near 1000 pounds unless it was some device that did lots more than just TPMS. FWIW, the one I have will also test vehicle remote fobs. It has a setup menu to select the year and model of numerous vehicles, so is not a single use item unique to one vehicle.

It is possible to damage a TPMS when dismounting a tire, depending on the equipment that they use, so it is prudent to verify that they're still working.

Regardless, on all of them that I"ve seen, the stem part can be removed from the TPMS so it can be replaced separately.

When TPMS were originally introduced, they thought they'd last the life of the car. Well, that hasn't been true. After about 6-years or so, they may start to get wonky. You may get more out of yours, or less...depends. It takes more out of a battery when it's cold out, and then, it does depend on how far you drive your vehicle as they're normally only fully on while they detect they're rotating in the tire.