h2oskiphil

Bought a 2010 550i with the M Sport package used about 2 1/2 years ago with around 80k miles. I've put 30k on it since then-absolutely love driving this beast. The previous owner put larger wheels and lower profile tires on the car (275/30ZR19's on the rear, 245/35R19's on the front, Style 95 offset wheels 9x19 front, 10x19 rear). Over time, I've started getting a tire rub on the fender lip on the rear tires when I hit bumps, and it's getting progressively worse. Originally it only happened when I had 4 people in the car and a full tank of gas and hit a big bump that caused a lot of rear suspension deflection....now it happens with just me in the car and the severity of the bumps that cause the rub is getting smaller-mild bumps cause it now. I've replaced the rear struts with the OEM Bilstein units, and that didn't fix anything. It's getting so bad that the fender lip on the driver's side is actually wearing a groove in the sidewall of that tire (there's a section of that fender lip that looks like it caught the tire and got dimpled out slightly, which caused even more wear to the point where there was rubber stuck to it). I bent that back, but it's still hitting and I'm not comfortable driving it for fear that it's going to destroy that tire.

Would spring wear over time cause this problem? Should I replace the springs with the OEM spring that came with the car originally (I THINK my dealer figured it out-realoem.com doesn't show a part number for the spring, and I understand that the spring part number is VIN specific)? Should I go aftermarket coilovers to raise the ride height slightly (or stiffen up the shocks) to make some room for those bigger tires and wheels to move around the way they need to? If so, any recommendations on coilovers?

I love the way the car drives right now....it's like a go cart in corners, but I have to do something about the tire rub before it destroys a tire going down the highway. Appreciate any advice or feedback.