I recently received my Mercedes-AMG C43 order and it arrived with Continental ContiSportContact SSR tires. I'd already purchased Michelin Pilot Sport 4S tires (non-run-flat) for the car and the dealer generously agreed to buy the Continental tires back from me. However, they couldn't get the car in to switch the tires for a couple of days, so I drove the car (gently, breaking it in) for about 300 Km. with those tires before the Michelin Pilot Sport 4S tires were installed.
To be truthful, the Continental tires were simply awful, thumping and crashing over every little imperfection in the road. Exposed aggregate pavement sounded and felt like driving on an early 1900's washboard. They also generated a fair amount of road noise. Initially, I actually thought the car had the suspension stuck in sport+ mode, everything was so harsh. I would have been very disappointed in the car had I been continuing with those tires!
I expected the Michelin Pilot Sport 4S tires to be a little better, but both my wife and I were shocked when we first experienced the difference. It's truly like a different car. It now rides beautifully, handles bumps and road imperfections as one would expect for lower-profile tires and the road-noise emanating from the tires has all but disappeared. I'm very happy with the Michelins and highly recommend them. Oh, BTW, their grip seems quite amazing. I doubt I'll get anywhere near their limits on public roads. Doing some autocross and track-day stuff should be fun.
It's really a shame that Mercedes would cripple an otherwise fantastic car with such lousy tires. Guess they never actually drove one with those tires.
If your Mercedes arrives with these tires, do what I did ... get a Slime tire-repair kit to drop into the trunk and switch out the Continentals for some good Michelin Pilot Sport 4S tires. You won't be disappointed!