Uneven Tire Wear

I would have the bushings checked in the front end. MIne had to be replaced at around 70K miles and eight years old. The alignment also has a lot of negative camber, around minus ten degrees, which aides in handling, however this will contribute to wear on the inside of the tire. It took me a couple different shops to get the alignment correct. Since only the toe setting is adjustable technicians will try to compensate the toe to achieve a straight steering wheel or even pulling to one side. This can have a negative affect. I had the camber/caster kit installed so the camber and caster could be adjusted. I don't believe that the alignment service at a normal tire center may not have the expertise to understand what is necessary in a complicated front end such as in a SL. I assume the front tires that are wearing unevenly. Twenty five thousand miles is about average tire life, varies from 20 to 30K. Have those bushings checked.

Your Indy is correct the camber causes more wear. However, my experience with the Michelin tires was not the best. Great handling, but less life, 20K at best. Toward the end with 4/32 left I started to experience bump steer from the rear end. Since the tires were worn and I now needed four season tires I went with a softer sidewall and higher treadwear level, 300, Yokohama high perf all season tires. The bump steer disappeared and now at 15K there is still over 50% tread left. This tire was more suitable for everyday driving with no appreciable loss in handling on the street.

In at least the early SL models, mine is a 2005 the bushing wear is a know problem and should be checked. The 2011 model may have improved bushings, Easy to check as the cracked rubber is readily visible when the car is up on a rack.