If your talking about the smooth looking spot just inside the outside tread, it's a rib that runs along the tire, Conti DWS. I'm not sure which AC systems I have, I'll probably post a few photos and see what people think. As for my plans, I'm thinking about possibly re doing parts of the interior that need to be done. Overall it's not in bad shape, just a few things that need attention, mostly I need to find a center console as the car came with pieces of one, but not enough to make anything of it. I'm currently underway of working on the suspension and I hope to at some point rebuild and build up the M10 or go in and swap the motor.