[Muz]

Hi Guys, I've got a 2007 pre lci 320d that was on standard msport 17's with runflats.

I just changed to 19" non runflats and I can't shift the annoying flat tyre warning on the dash. I've read how to do it over and over, and even a BMW salesman has had a go, but sure enough the icon comes back.

is the tyre pressure calculated by the rotational diamiter of the tyre? or is there an rf sensor in them on my model?

[Dr Dave]

Are all your tyres the same size across the axles?

[Muz]

Originally Posted by Dr Dave

Are all your tyres the same size across the axles?

Huh?

Do you mean staggered? if so the new ones are staggered as were the originals.

The new ones are larger in width and diameter

[HighlandPete]

Originally Posted by Muz

Huh?

Do you mean staggered? if so the new ones are staggered as were the originals.

The new ones are larger in width and diameter

But are they to the correct size for the BMW? If you have a wrong size, or aspect ratio, you could be signalling a puncture due to wrong RC's.

Best to post the tyre sizes, front and rear, it may make sense.

HighlandPete

[Dr Dave]

I think we've identified the problem.

The runflat system compares wheel rotation speed - and not via RF pressure transmitters in the wheels (In the UK, anyway)

[HighlandPete]

Yes we are using the indirect system via the wheel speed sensors (originally ABS sensors) here in the UK. The US uses the direct system with pressure sensors in the wheels. So if we have a pair of tyres of the wrong size, there is a conflict. Either the TPWS can't be calibrated on the setup sequence, or it immediately sees a fault.

HighlandPete

[Muz]

Ahhhh, yes the new tyres are fractionally bigger.

So how do i recalibrate it?

[HighlandPete]

Not sure what you mean by recalibrating it? Do you mean changing the parameters/functions which depend on wheel speed? The system is also involved in DSC function, so more issues may throw up, particularly as you push the limits of the car, if this really is a tyre problem.

What have you done, fitted bigger tyres with a different RC on one axle only? You do need to post the sizes, it could answer the problem.

HighlandPete

[script]

I've an 07 and I'm still not 100% sure on my type of system,its got metal air valves so a few early cars may have the US system.(chip in with thoughts)

It should reset regardless obviously though.

[m1bjr]

@script
The metal stems do not signal RF transmitter (US) types - they are just metal stems.
A lot of oem cars have them, they seem very common on the original 230 style alloys, I have them.

Calibration:
Do you have iDrive or not?

The method differs, but essentially you reset the warrning whilst stationary and with the correct tyre pressures dialled in,
then go for a drive to 'initialise' the system. Its essentially self-calibrating.
If it won't, then you have other issues.

Its' all in the handbook - best to read that bit

[Muz]

I don't have i'drive on my 3 series.

I went from standard staggered 17's to 19! 265/30/19s

I thought it would be a common thing :s

[HighlandPete]

What tyre size have you got fitted on the front?

You are doing the 'reset' with the engine running and driving off after you sequence to the second tick symbol?

If still not to the problem, one other thing, not knocked or damaged a sensor wire with the new rims have you?

HighlandPete

[doughboy]

Plenty of folks run 265/30/19's.

Either your system is faulty or you are not resetting it properly.

It makes no difference if they are slightly larger diameter, or even uneven (part worn) diameters as resetting the system will zero out any imbalance.

Any change from then will be flagged as a puncture.

[kaishang]

Even if the tyres are bigger than the OEM tyres, as long as they are bigger by the same amount it should not make any difference to the tyre pressure warning system. If they have a bigger rolling diameter though, it will mean your speedometer and odometer under-read.

[Muz]

I don't get a tick, i get a small triangle on the left of the menu pointing to the right if i tap the button on the stalk it ckears the error and it's back in about 3 seconds, the same if i hold it in for 5 seconds

It doesn't give me enough time to drive off for anything to calibrate and there's no sign of a tick

I'll video it tomorrow

I'm sure i'm going wrong somewhere!

[hmi1750]

-Start the car.
-Use the stalk to toggle to the tyre pressure setting
-Push the stalk button
-Push again and hold for 3-5sec
-The tick appears
-Engage gear and drive away

Should now be fully reset and not come back.