TPM Malfunction? (A pic would have really been helpful). Are you getting a malfunction warning or just a low tire warning due to changing over the wheels?
Did you reset the TPM system after replacing the wheels? Any wheel/tire change or inflation...the system should be reset by going into iDrive and scrolling to the INIT or RESET icon along the left side of the screen...and the engine needs to be running to initiate the change...then you proceed to drive.
I'm not clear if you have a malfunction or you just need a reset? But the warning probably has nothing to do with 19" staggered wheels on the rear. It's more of the sensors aren't communicating with the control module...or you need to reset/initialize the system with the change of wheels.
Also, BMW changed the TPM sensors and perhaps your old sensors don't communicate with your new car. If you remember the VIN of your old car...input that data into one of the online part database sites (like
www.realoem.com )...and pull up the correct 11 digit BMW part number for the sensors used for that car...then compare that to your new car and see if they use the same part number. If they don't...then you've found the problem...you'll need to install new sensors that are compatible with your new car.