these wont be the lightest option, but pretty good value:
http://www.montyswheelsandtyres.com/...For=&PT_ID=134
I ran A048s on 18" M3 wheels for a while in 2007, they work pretty well, fit over the AP calliper.
Only thing with A048s, is I found them quite sensitive to heat cycles, so took longer and longer to get up to temperature as they wore down.
look ugly compared to CSL rims though
