I was wondering, are the OEM 348x36mm rotors floating/Al hat or solid one piece iron?

Is there a(n) euro lightweight two peice rotor option (say like a Euro floating rotor or something)

 

It's a floating two piece type, aluminum hat with ventilated iron disc. Just like the M5s minus drilled rotor and bigger diameter.
Cooler disc - due to higher heat dissipation rate of aluminum hat as compared to cast iron and allows the disc to expand and contract freely without stressing the hat. This helps prevent the disc from warping or cracking.

Aftermarkets are mostly one piece solid iron (non-floating). Non-floating assemblies are easier and less expensive to make because they do not require the same precision as floating type assemblies.

 

Thanks very much Joe!!!

 

Dude, Joe is like brake PRO.

 

All I know is they are HEAVY!

 

Nah, what does he know about brakees - look at his car

+1 Great info Joe

 

Joe, will 17in wheels clear the stock 348mm setup?

 

They might fit. Style 116 (17 x 7.5) was standard on 545i with all-season tires (225/50/17).