At the time I bought my car, I also bought a spare set of unused OEM wheels and tyres off eBay from a chap who upgraded his new 135 to bigger wheels. For only a grand, I felt it was a good deal and the plan was to wear out my originals, swap the wheels and then fit my originals with Winter tyres so that I could swap over between winter and summer.
My question relates to the TPMS senders in the spare wheels - do they have to be synced with the car?? Is this a job for the dealer or will the new wheels sync merely by resetting the tyre pressures in the iDrive? (assuming the latter isn't mid reboot)
The dealer tells me all that is needed is to reset the pressures in the iDrive and the system should automatically sync with the TPMS senders in the new wheels - I suspect the info is correct.
Whilst on the subject - can anyone answer the following . . . . . Prior to the latest cars being fitted with TPMS, the older generation had a more basic tyre pressure monitoring system which used the ABS to monitor the differential wheel speeds in order to detect a puncture of loss of pressure. So, you've got a tyre that's slightly deflated, it's radius is reduced at the point of contact with the road and thus, at any given road speed, the rotational speed of the wheel is increased, relative to the other wheels. Clearly, there are other things that will affect any differential in rotational speed, the most obvious being tyre wear, wheel size and cornering, where the outside wheels have to rotate faster. This explains the need for a "reset" and so . . . with the older ABS system, you pump up your tyres to the correct pressures, press "reset" and go for a short drive to allow the system to monitor the relative speeds of each of the wheels. Once the system has this data, any divergence from these differentials and in particular, when one wheel is found to rotate faster than it should compared to the others, will immediately trigger a tyre pressure warning.
OK - so now we have senders inside the wheel which wirelessly transmit the actual pressure from each tyre directly to the iDrive controller and presumably, if the pressure falls either above or below a manufacturer-set tolerance, a warning is triggered.
So . . the question is, why does my car still require a TPMS "reset" after pumping up the tyres and the mandatory 4-5 mile drive in order to fully complete the set up?? It tends to suggest that perhaps the newer cars are using both systems in parallel. Perhaps if the battery fails in the TPMS senders, the system falls back on the old school differential rotational speed and the ABS system to detect a puncture or loss of tyre pressure. Does anyone know the answer??
My question relates to the TPMS senders in the spare wheels - do they have to be synced with the car?? Is this a job for the dealer or will the new wheels sync merely by resetting the tyre pressures in the iDrive? (assuming the latter isn't mid reboot)
The dealer tells me all that is needed is to reset the pressures in the iDrive and the system should automatically sync with the TPMS senders in the new wheels - I suspect the info is correct.
Whilst on the subject - can anyone answer the following . . . . . Prior to the latest cars being fitted with TPMS, the older generation had a more basic tyre pressure monitoring system which used the ABS to monitor the differential wheel speeds in order to detect a puncture of loss of pressure. So, you've got a tyre that's slightly deflated, it's radius is reduced at the point of contact with the road and thus, at any given road speed, the rotational speed of the wheel is increased, relative to the other wheels. Clearly, there are other things that will affect any differential in rotational speed, the most obvious being tyre wear, wheel size and cornering, where the outside wheels have to rotate faster. This explains the need for a "reset" and so . . . with the older ABS system, you pump up your tyres to the correct pressures, press "reset" and go for a short drive to allow the system to monitor the relative speeds of each of the wheels. Once the system has this data, any divergence from these differentials and in particular, when one wheel is found to rotate faster than it should compared to the others, will immediately trigger a tyre pressure warning.
OK - so now we have senders inside the wheel which wirelessly transmit the actual pressure from each tyre directly to the iDrive controller and presumably, if the pressure falls either above or below a manufacturer-set tolerance, a warning is triggered.
So . . the question is, why does my car still require a TPMS "reset" after pumping up the tyres and the mandatory 4-5 mile drive in order to fully complete the set up?? It tends to suggest that perhaps the newer cars are using both systems in parallel. Perhaps if the battery fails in the TPMS senders, the system falls back on the old school differential rotational speed and the ABS system to detect a puncture or loss of tyre pressure. Does anyone know the answer??
