One of my 300 SEL's has Monroe Sensa-tracs on it that the previous owner had put on right before I bought it. Those paired with some Kumho ASX 225/60/15's give it quite a bit smoother ride than my other 300 SEL which has ---

Stock suspension with BFG Traction T/A V rated 225/60/15's... around town at low speeds the thing can be quite punishing on the rough streets, but I believe a lot of that is from the tires. Those BFG will let you feel any tiny variance in the terrain. Once you get the thing up to 65 mph+ it all smooths out. I use this as my highway traveling machine so it works out well.

Tire pressure has a huge effect on the ride quality in these cars. When I first got the car with the Monroes on it, the owner was running the old Michelins at 28psi all around. It felt like it oozed around at that pressure, so I pumped it up to 32/34 and it turned it into a totally different machine.

__________________
(2) 1988 300 SEL W126