I leased a 2024 C300 4Matic AMG Line with 18 inch wheels a few weeks ago. Overall I am pretty happy with the car but the ride is a little stiffer than I would prefer. I live in Minnesota and worn out concrete roads are not helping either. Most reviews (of AMG line C300 specifically) say that the ride is smooth and comfortable but that is not my experience.

Currently I have factory Continental Procontact Gx SSR runflat tires, and I think they might be contributing to harsh ride. Since I live in Minnesota, I have been considering getting all-weather tires. I looked into Bridgestone WeatherPeak, but it is not available in XL load rating. Other options are Michelin Crossclimate 2 and Pirelli Cinturato Weatheractive. Would I experience a significantly smoother ride if I make the change? I measured threads on my current tires (6/32) and they should be good for a while. A new set would be ~$1200 including installation and I am not sure if it is worth it.

I really don’t care for being able to drive if I tire is flat. I have been using regular tires for years and never had any issues. My dilemma is how much of the firm ride is caused by the suspension vs run flat tires and whether it is worth to spend the money on a new set of non run flat tires for the sake of comfort.

Run flat tires do have stiffer sidewalls, but these days they are factored into the suspension tuning. Before you go and buy new tires, sort out your tire pressure. Most people use tire pressures that are too high. The ones listed on the driver's door sticker are only the max load pressures. They are technically only suitable for when the car is loaded to its gross weight. Open the fuel door and inside you should see a black sticker with more detailed tire pressure information. Look for the lower normal load tire pressure and adjust yours. The normal load pressure is for normal driving mostly by yourself and not much cargo in the trunk. For reference, below is the sticker from my C63. Yours will have fewer options due to lower top speed and such. The normal load pressures will give you a more comfortable ride. Also keep in mind that the tire compound gets stiffer as temperatures drop. All-season tires have a wider temperature range, but they will still be stiffer in the winter compared to summer. If after this you still feel you want different tires, then I can recommend the CrossClimate 2. Have it on my wife's car. Excellent tire all around.

Thank you for your response. Normal load is 37 psi according to fuel door. Vehicle shows 37-38 psi across all tires (it is 25F outside).

I grew up in Europe where it is mostly smooth asphalt, and moved to the US a few months ago so maybe that is the issue and I am supposed to get used to roads here. I will give it a few more weeks before making a decision on new tires.

First off, get a proper tire gauge and measure the pressure manually when the tires are cold. Don't rely on TPMS. It's not very accurate. Yeah, 25F is cold. Wait till it warms up in spring/summer and see how you feel then. Having said that, welcome to the US and yes, roads are crap here. I'm originally from Switzerland. You gonna have to adjust. Especially in the parts of the USA that see big temperature swings between summer and winter, the roads get really bad with potholes and broken pavement. Road pavement in the USA sucks. There's no proper foundation under the asphalt like they do in Europe, so the pavement just deteriorates. It's compounded by the much heavier semi trucks that drive around here compared to Europe.

I dumped the Continental GX SSR run-flats for a set of Vredestein Quatrac Pro+. They are cheaper than the Michelin or Pirelli all-weather tires and ride very nicely even at 42 psi.
They have the 3-peak mountain/snowfake symbol and I recommend them highly n the 18" size. The 19" are not XL load rated so, not recommended.
I also got a M-B Airlift inflator and sealant kit on eBay for <$100 so I don't worry about run-flats.

I swapped out the factory Bridgestone runflats on my 2022 and for the Michelin pilot sport 4 all season. Best quality of life improvement for the car - much more comfortable and less noise. More importantly, I can now drive over poor roads that would have (and did) pop my run flats.

The ride on the C300 is only smooth if your road conditions are smooth. Rough terrain will be felt since it's one of the more basic suspension systems (no airmatic) paired with low-profile tires. A friend's GLC 350e came with Continental 19" runflats. The car feels like it's driving on air since it has rear air suspension and high-profile tires.

Ya run-flats are more susceptible to road damage than traditional tires. They can bubble or bulge and can damage the rim. To compensate this, you inflate the pressures higher which further ruins the ride quality.

Depends what you compare it to. Having multilink suspension on front and back is not really that basic. Most popular brands use Macpherson in the front.
I have "sport suspension" and find it as a perfect balance between handling and comfort. Yes, it's bit stiff sometimes, but smaller road imperfections are actually handled very, very well. Much better, than in my previous, "popular brand" car, which had softer suspension and didn't drive as well.
It's better than i.e. 3 series BMW, not to mention most "popular" cars.
Of course, it would be better with airmatic, but it is what it is. You want airmatic, get E-class. This is the way most manufacturers are thinking. They cannot put all the best in cheaper cars for a reason.
I like this suspension very much, but i would not go with 19" wheels on it

I heard European C class had airmatic offered but it might had been only on W205 and no W206 have it as an option, was that true?

Yes, W205 was available in Europe with AirMatic.
For W206 that option is no longer available, with one small exception. You can still get AirMatic FOR REAR AXLE ONLY, if you go with plug-in hybrids. This is to compensate for weight of the traction battery. Am not sure if AirMatic is standard for plug-ins or if it's an option, but it's the only way to have some kind of air suspension in W206.

Ah air suspension on one axle... That ride would be very strange but thanks for confirming what I heard.

For those of you who changed over to non-runflats, what do you have in the trunk in case you do get a flat?
We pick up a C300 next week, and I will probably swap out the tires.

All factory non-run flats come with the MB TireFit kit. It’s an air compressor and sealant which is used for roadside puncture repair. Definitely not as convenient as a spare but the size of the first aid kit. I don’t think even a collapsible spare would fit under the trunk liner.

On the ‘25 GLC 350e the rear air suspension comes standard. I’ve rode in it a few times now and this definitely makes a difference - much smoother than the regular GLC 300.

Interesting, I always wondered how does having spring in the front and air in the rear will play along but sounds like it is pretty peaceful.

This is not uncommon. BMW has done it for years on the 5 series Touring models for example. It's done for very specific reasons and works well. The weight over the front axle is fairly constant, whereas the weight over the rear axle depends on whether you have rear passengers, how much you stuff in the trunk and if you are towing a trailer. So an air suspension in the rear can adapt to those weight changes and provide much more comfort and stability than a coil spring suspension. The hybrid models already have additional dead weight in the rear from the battery, so air springs in the rear help with managing that mass and provide more comfort and stability. Nobody sits directly over the front axle, so a lot of the comfort in a vehicle comes from the rear axle, especially for the rear passengers as they essentially sit directly over the rear wheels, but even the front passengers benefit from it as they roughly sit in the middle of the car. In case of BMW and MB actually slightly behind the middle as both place the engine mostly behind the front axle as opposed to Audis where the engine hangs out in front of the front axle and the passengers sit further forward.

I did not know that at all, is it uncommon for Mercedes at least?