The size of spacer will depend on the offset of the wheels you use. If they are OEM wheels, 15mm will be fine. And IMHO aggravated bearing wear would only occur if you used some really wide spacers (30mm+).
E92 pre-LCI 325i
- Ohlins R&T; H&R spacers; M3 strut brace; Meyle HD droplinks and top mounts; Swift thrust sheets; BMS clutch stop; BMS CDV; RE g/box mounts; Saikoumichi OCC; K&N; Cyba scoops; B A diff brace; BMW Perf Exhaust; M3 rear spoiler; M3 white dash LEDs; LED Angels; BMW Perf black grille; CSL reps; SSDD carbon diffuser; Monster Wrap black roof