just had a though...how does the tyre pressure thingy work?

[zippster]

as the subject suggests, how does the tyre pressure monitor thing work if you change your wheels and tyres? ive read that its taken from the ABS sensor and then ive also read that its taken from a sensor on the wheel?

my concern is that i have changed my wheels and tyres to CSL's(baaaaa i know) and wonder if the TPM will still work?


anyone know?


thanks in advance


Andy..

 

[Z4monster]

Older cars use the ABS sensors and wheel rotation. Newer cars use the TPMS which has a sensor in each wheel. As yours is a new M then unless you've transferred the sensors you've lost the system AFAIK.

Sorry to be the bearer of bad tidings.

 

[zippster]

ive just found this on bimmerfest can anyone confirm that this is the case?



In the UK you may not have tyre pressure monitors (TPM) on the wheels of any Z4M. The US certainly had them for 2007 onwards due to federal regulation, but the Canadian 2007 & 2008 models retain flat tyre monitoring (FTM) using the ABS sensors. The most reliable way to tell without removing the tyre from the wheel is whether you have rubber or aluminium valve stems. If rubber, you don't have the sensors, but use the FTM system.

 

[zippster]

this is apparently what the sensors look like.

original bimmerfest thread here..

http://www.bimmerfest.com/forums/showthread.php?t=284199&highlight=csl+tyre+pressure

 

[Curtis]

Maybe it's just an Alpina thing but my car came with metal valve stems as standard but has the older ABS sensor system.

 

[zippster]

also just checked on realoem and that new site http://bmwfans.info/original/ and cant find any sensors for my car??


arrrgh can someone confirm if i should or should have them, i was told i dont have them but i want to be sure.

just checked in my garage and the old wheels have rubber valve stems as my new ones do..

looks like its a US thing as if you choose europe the parts dissapear.


anyone?

 

[zippster]

ok for all those interested, my book says that that the RPA works in rolling radius changes, and this in turn alters the speed of rotation. this is detected and interpreted as a puncture.

so i think im right in saying that us UK'ers dont have the sensors in the wheels anyways (unless you have metal valve stems??)


hurrrummmmpfft... my brain hurts, done enough reading for tonight.

cheers

 

[Wondermike]

zippster, there's an easy way to check. Reset the gauge, drive a few miles, and then go and let half the air out of a tyre, and see if it responds. If it doesn't you know you messed up :lol:

:smart:

 

[thebighash]

my 2007 Z4MC is Euro spec & has the ABS thing sensors.. no real TPMS.

when i upgraded to 19's i found this out & i think all non-US spec cars are like that

i say u don't have the TPMS so ur system should still work properly

 

[Andrew_Morris]

Perhaps I'm being a little naive here but wouldn't the quickest way to find out be to let out some air and take it for a short trip?


Let us know how you get on....


Oh I just re-read the post and can see wondermike came up with the same idea ......

 

[zippster]

nah i dont want to run the risk of damaging my rims or tyres driving around with low pressures, im happy that my manual says its done by the ABS and also for a euro spec car i cannot find any reference to the systems being fitted by the factory.

to have the sensor on the wheel (the sensor sits behind the valve) there will be a non rubber valve fitted to the rim so as my OE double spoke rims have rubber flexi valves they dont have the sensors.

also realoem and that other site(url in previous post) do not list a part number on the TIS for euro spec cars.

besides i would never trust it anyways and am used to checking my tyre pressures every couple of weeks anyways.

Im happy that i dont have them and would go as far to say that all of us UK'er dont have them either.

Cheers

 

[Screamer]

Yep - all UK, and maybe all other non-US cars have the ABS system, and therefore no sensors in each wheel. Had the same dilemma a few days ago myself when going for my new CSL's. Like you say, the way of knowing is whether you've got rubber or metal valve stems (not to be confused with the caps - it's the stem that we're interested in), because the metal stems are used by sensors in the wheels as aerials to transmit pressure info to a receiver in the car. Rubber stem = no aerial = no sensor. Although the obvious first reaction is to think we've been shortchanged with a lesser system, it's precisely for that reason that I think our's is better. Because the sensor system is so accurate, there have been many reports of alarms being set off on trackdays and from more agressive driving, whereas our more simplistic system is less likely to be tripped up by the same thing, given that it is simply comparing the rotation of the wheels. It also means we can swap wheels & tyres without having to take our existing ones apart to get at the sensors!

 

[zippster]

Cheers Screamer.... its always nice that someone else confirms the same findings.



now..... anyone want a set of M double spokes



Thanks


Andy..

 

[Wondermike]

...Although the obvious first reaction is to think we've been shortchanged with a lesser system, it's precisely for that reason that I think our's is better...

I also think this system is better, it detects losses in pressure just fine.

 

[Screamer]

Cheers Screamer.... its always nice that someone else confirms the same findings.



now..... anyone want a set of M double spokes

No probs :wink: Any other q's you have leading up to you buying new wheels, let me know because i've probably had to work out the same things with mine..!

As for your existing wheels, if you stick 'em on eBay (even like I did at £900!), you'll get a good few offers of around £500. Quite a few people leave their numbers so you can call them if you want. That's how I got £650 for mine - firmly offered £500 by e-mail, and then negotiated that up to £650 over the phone. As others have said, given the different widths of the front/rear wheels, and that they apparently have 'aggressive' offsets, I think offers in that region are pretty good.

 

[zippster]

cheers again, just agreed £600 from a fellow coupe owner (from the lotus forum that im still a member) he lives local and will collect them. so to me that sounds fair.

still doesn't sound much when you consider how much it was cost to replace them, but hey csl's are worth it.