When initializing the once set inflation tire pressures serve as reference values in order to detect a flat tire. Initialization is started by confirming the tire inflation pressures.
Do not initialize the system when driving with snow chains.
On the Control Display:
1. "Vehicle info"
2. "Vehicle status"
3. "Perform reset"
4. Start the engine - do not drive off.
5. Start the initialization with "Perform reset".
6. Drive away.
The initialization is completed while driving, which can be interrupted at any time.
The initialization automatically continues when driving resumes.
BMW X3 Service & Repair Manual > DTC: Tire pressure monitor system reminder
NOTE:
If a tire pressure has been adjusted, or a wheel or tire has been changed or
replaced, or repairs have been made to air spring suspension, the TPM system
must be reinitialized. System must be reinitialized both before and after pulling
a trailer.
CAUTION: When driving with snow chains or ...