Just reviving this thread for the benefit of any M135i owners in Australia. Mine's just hit 19000km and the shoulders of both front PSS are just about gone. Must have been that run through the Victorian alps I did over the last couple of days.
If you're happy to try another brand, and can get in quick enough, Goodyear Eagle F1 Asymmetric 2 in 225/40 R18 92Y are $159 + shipping. I've just ordered 2, and it still works out quite cheap even though shipping to Vic is $35 per tyre and fitting/balancing are excluded.
It'll be interesting to see how they perform compared to the PSS, which other than the wear rate, have been absolutely flawless.
Source:
http://www.ozbargain.com.au/node/178977
Seller (Perth based):
http://tyrebuy.com/store