The original set of Roadstars (also known as BMW Style 40) that were on the car when I purchased it were showing their age and had sustained more than one curbing event. I wasn't enthusiastic about mounting new tires on beat up wheels and I also didn't want the car up on jack stands for a month waiting for the wheels to be refinished.
After looking at available aftermarket wheel options that would fit the M Roadster, I couldn't find a 17" wheel style that I liked better than the OEM Roadstars. What is it with BMW aftermarket wheel styling? Most choices with the correct fitment were variations of the same spiky antler look; my tastes lean towards painted steelies with Baby Moon hubcaps, old school American Racing "Torq Thrust" in Antrhacite gray, or maybe a set of chrome Cragar S/S five spokes. Yes, I am a geezer. All three are not particularly lightweight, but I have no plans to track the car. If I ever go with aftermarket wheels, to get the right sizing and styling I'm pretty sure I'll be looking at custom built wheels.
After an unsuccessful search for a nice set of used Roadstars, I took the plunge and bought a new set:
The rear Roadstars are 17" X 9” wide with a +8mm offset (ET8); fronts are 17" X 7.5" wide with +41mm of offset (ET41).
Apparently BMW changed Roadstar wheel suppliers over the years; the original set of wheels have "OSO" cast around the valve stem flange:
The new set of Roadstars were manufactured by BBS:
BBS wheel valve stem flange:
The roundel center caps for the new wheels are also somewhat different than the originals: