If you run Metzler Z6 on your BMW, you know that the KGT, RT, etc., take special tires. The RT takes a "K" front and a "C" rear, for example.
The new Metzler Interacts have a "C" rear tire (just a standard front for now) but I have searched a lot to find it onlinle. Finally, I see AMT sells the special tires for BMW. If you need new shoes, and you want Interacts, go to:
The prices are good but you have to add shipping. My set for the R12RT ran $311 out the door.