In US/CAN we don't have high speed like over EURO so we don't need that crazy negative camber.
To prolong the tires life. You need the rear cambers kit from BMW Parts and BMW Accessories | Bavarian Autosport ( small/minor moddification need)to get the custom cambers kit to work correctly.
After all the installation is done you need to get an alignment done and set the rear cambers to 0.05* .