I've got a '97 S500 sedan. I just bought a set of 19" rims with 235/35's all around as part of the package. It was immediately apparent that the car needed more meat in the rear. I picked up a hardly used set of Michelin Pilots, size 275/35's. This would give me a 4% difference in circumference front to rear. Before I put the 275's on my car, is the difference enough that it's going to screw with my ABS?

 

the proper size for the front is 245/45/18 (that closely matches the stock size)

I have had 245/45/18 front, and 275/35/18 on the rear (rims off a w220 S55) on my previous s500 and it ran fine... No issues w/ ABS, although cruise stopped working

in my current coupe, I have 245/45/18s all around and since it's almost identical to the rolling diameter of stock, I have had no issues. Ideally, you should not be more than 3% off the factory spec.

use this link to determine the proper size:

http://www.1010tires.com/TireSizeCalculator.asp