[oVeRdOsE.]

Hi,


1. From my reading, there's no TPMS on the canadian F25, they use abs sensor.

In fact, the stem on the OEM wheels are in rubber.
(picture last post here : https://www.xbimmers.com/forums/show...highlight=tpms )

2. I got new X5 wheels on the X3, no TPMS nor MPSS.
Rear size is 275-40-19 , front 245-45-19. Equal diameter.

3. Got the warning pressure code , 80km/h max .

4. I have no flat tire. ABS is working.

What could it be ?

[Aspen235]

Did you reset the Flat Tire Monitor in i-drive?

[oVeRdOsE.]

Originally Posted by Aspen235

Did you reset the Flat Tire Monitor in i-drive?

I will try. You've make me think this might be because of the winter / summer tire size difference.

winters are 225-40-19.

thanks !

[softsign]

It's definitely the size difference. The Flat Tire Monitor (FTM) is not a true TPMS. Per the manual:

The system detects tire inflation pressure loss on the basis of rotation speed differences between the individual wheels when driving.

In the event of a tire inflation pressure loss, the diameter and therefore the rotational speed of the corresponding wheel changes. This will be detected and reported as a flat tire.

The system does not measure the actual inflation pressure in the tires.

[...]

Initialize the system after each correction of the tire inflation pressure and after every tire or wheel change.

[oVeRdOsE.]

thanks guys. it helps me to understand the system.

[pokerface]

Check pressures then do a reset. Unfortunately temperature fluctuations can also set off the warning.

[oVeRdOsE.]

Originally Posted by pokerface

Check pressures then do a reset. Unfortunately temperature fluctuations can also set off the warning.

My post was more a ''how the system is working'' question.

Pressure variation shouldn't throw a code since I dont have tmps. Unless I have a flat and the rotation variation is enough.

Also, on my winter setup I have 1% difference of tire outside diameter front/rear, and this is NOT enough to get a code. (i re-use almost new hakka 8 on my old rwd car)

Strange enough since when I put the winter tires, I had no code, and putting back the same summer's I got a code.



Anyway, I very like this ABS setup instead of a real tpms, since there's way less chance to fail. Also Im the type of person who check tire pressure every month, so no issue here.