It's more like the tires are wearing down the plastic nub.
I haven't had time to look into it. It doesn't rub all the time but hit a half decent bump or a dip in the road and it rubs. Also, it depends on the tires too. Different brands are different widths even though the size is the same. I'm running Hankooks in the stock ZHP size
Dinan CAI &Throttle body, ESS Tuning TS2, Bimmerbrakes gen3 headers, UUC SSK & DSSR. Achilles oil pump, VAC oil pan baffle
M3 Motor mounts, UUC Trans mounts, Modified clutch style LSD 3.15, TMS front subframe reinforcement, Koni Yellow sports,
H&R sport springs, UUC sway bars, BMW Perf. Rotors, UUC SS brake lines, Hawk HPS pads, CSL replica wheels,
Rotora strut bar, FXR HID conversion, M3 Mirror conversion, BSW stage 1 speakers