I have a brand new set of wheels sitting here that i'd like to put on my 2007 E550W4M with Sport pkg, with airmatic....if they'll work.

They're 18x9.5 (all 4) with ET35.

I would be using the stock tire size 245/40/18.

Will they fit without issue?

Anyone?

9.5 will not fit on the front of a w211 without issue as they will stick out of the fenders

That wheel would fit the car fine, it would be considered a slightly aggressive fitment. It will come right to the fender, having them machined to a +40mm offset would be much better.