[Piers]

I feel dirty....I havent checked them in the 18 months I have had it, relying on the TPM

[The Beast]

Originally Posted by Piers

I feel dirty....I havent checked them in the 18 months I have had it, relying on the TPM

You might want to check them, the TPM doesn't seem to flag up pressure loss until it's pretty low or there's a sudden loss. Mine was 16 PSI when it flagged that the tyre was low. Also my F10 seems to loose pressure a lot more regularly than previous BMW's. I would check previous cars and the pressure would hardly change over very long periods of time, however the F10 seems to loose pressure every time I check. Therefore I'm checking it more regularly, not sure if it's to do with the 20's and ultra low profile tyres...

[SpeedTrip]

TPM comment last summer - had hit a helluva pothole & the TPM sprang into action - no damage but made me realise it wasnt a good substitute for a real check !

http://f10.5post.com/forums/showthread.php?t=1000692

[The Beast]

I guess it's primary function is to monitor a sudden loss in pressure, BMW only installed these as standard when they moved to run flats as it is not immediately apparent if you get a flat.

You need to upgrade to the full system which displays tyre pressures in idrive if you want to monitor small fluctuations in tyre pressure

[HighlandPete]

Originally Posted by The Beast

I guess it's primary function is to monitor a sudden loss in pressure, BMW only installed these as standard when they moved to run flats as it is not immediately apparent if you get a flat.

You need to upgrade to the full system which displays tyre pressures in idrive if you want to monitor small fluctuations in tyre pressure

TPWS (Tyre Puncture Warning System) is the indirect system using wheel speed sensors, it is as you say only a warning system for when we have a problem. BMW also refer to this system as FTM "Flat Tyre Monitoring". Hence why physically checking the pressures regularly and resetting the system after every tyre pressure adjustment is essential.

TPM (Tyre Pressure Monitoring) is the direct system with pressure sensors, much easier to keep an eye on current tyre status.

HighlandPete

[The Beast]

Originally Posted by HighlandPete

TPWS (Tyre Puncture Warning System) is the indirect system using wheel speed sensors, it is as you say only a warning system for when we have a problem. BMW also refer to this system as FTM "Flat Tyre Monitoring". Hence why physically checking the pressures regularly and resetting the system after every tyre pressure adjustment is essential.

TPM (Tyre Pressure Monitoring) is the direct system with pressure sensors, much easier to keep an eye on current tyre status.

HighlandPete

Thanks for clarifying the official terminology of the two systems

[Piers]

I need to sort this...I have 19" 351's, what pressures should I run, mainly me only in the car. Thanks chaps

[Pottsy]

32/33 set when everything (tyres and weather) is cold.

[AP]

Well I've tried 2.3 bar all round and I think I've noticed an improvment in terms of less tramlining. So that's up 0.1 bar on the front wheels .
I'll see how it goes but it feels encouraging so far, can that small change really make a difference?

[HighlandPete]

Originally Posted by AP

Well I've tried 2.3 bar all round and I think I've noticed an improvment in terms of less tramlining. So that's up 0.1 bar on the front wheels .
I'll see how it goes but it feels encouraging so far, can that small change really make a difference?

In my experience with RFTs, yes!

When I first tested RFT shod BMW models (E60 was the first) I had no idea that the working parameters of the run-flat can be so tight, compared to non run-flat tyres. Wasn't until getting my E91 330d and discovering the problems and how 0.1 - 0.2bar could make a marked difference to how the car drove, did I realise that a lot of my test drives (when I found all sorts of weird characteristics) and got put off models, wheel and suspension combinations, was possibly influenced by the wrong tyre pressures.

It is the working pressure which is key to getting it correct, the run-flat typically take longer to warm up, when cold and wet can have a completely different feel than when fully warm. Much more marked than the conventional tyre.

HighlandPete