SLK 350 tyre footprint on 17's and 18's

[eng622]

I see the rear tyre width is 245 for both 17 and 18 inch wheels wheras I would have expected the 18's to have a larger footprint. I know the profile goes down from 40 to 35 but is there any gain in handling with the 18'S and how much sacrifice in ride quality, if any, do they give.
I see the 18's were offered as a kit with the sports suspension so what was the MB thinking behind this and what are owners experience in practice.

 

[Bobby Dazzler]

I think there will be a small gain in handling and a similarly small sacrifice in ride quality if switching to 18s from 17s. Whether you'd notice, then that's a different question...