TPM on MY05

[sessions]

I just switched out my stock 18" 108 rims for 19" VMR wheels on my 05 Z4.

Since the TPM sensor measures the rolling radius of the wheel to calculate the change in tire pressure, do my new rims throw off the TPM sensor because the circumference is now 1" larger?

 

[AlanJ]

The BMW TPMS on your model uses the ABS wheel speed sensors to monitor the rolling radius of the wheel and tire assemblies. Rather than directly monitoring tire pressure, the ABS measures the rotational speed of each tire. If one tire starts to spin faster than the others, the ABS determines that a tire has become smaller and has likely lost air pressure. This is done by measuring tire rotations within a given distance. A tire that has a reduced rotation that meets a predetermined percentage is considered to be low on air pressure. Therefore providing all your rims are the same size then the comparison will remain stable unless one wheel punctures and the rolling radius reduces and the comparative rotation changes.

 

[Redzedfour]

Might be worth PM'ing RichardG as i know he is running 19" VMR's just too see if he has had any probs.

 

[sessions]

The BMW TPMS on your model uses the ABS wheel speed sensors to monitor the rolling radius of the wheel and tire assemblies. Rather than directly monitoring tire pressure, the ABS measures the rotational speed of each tire. If one tire starts to spin faster than the others, the ABS determines that a tire has become smaller and has likely lost air pressure. This is done by measuring tire rotations within a given distance. A tire that has a reduced rotation that meets a predetermined percentage is considered to be low on air pressure. Therefore providing all your rims are the same size then the comparison will remain stable unless one wheel punctures and the rolling radius reduces and the comparative rotation changes.

thanks dude