////AMG_C43

My 2019 C43 was originally delivered with 19” Pirelli P Zero run flats that I changed over to Michelin PS A/3+’s within the first 1k miles of ownership. Over the next 9k miles driving on these tires, I kept my cold pressures at the factory recommended settings of 36 front and 33 rear.

While these tires did marginally improve the car’s ride, I still felt that the suspension was unnecessarily harsh at low speeds. Further, the ride had a low speed coarseness on all but the smoothest of roads. It just made no sense to me that the AMG engineers would have intentionally dialed-in such crude low speed damping characteristics on this car.

After much experimentation and measurements, I have reduced my cold pressures down to 33F and 32R. Just this one change has made a marked improvement in the car’s ride. These are exactly the same pressures Mercedes recommends for the C63S running 19”/20” non run flat tires. (see attached discussion link)

https://mbworld.org/forums/c63-c63s-...-pressure.html

Just relating my experience. YMMV

Sailorlite

It does make sense that optimum pressures could be different after replacing the runflats with conventional tires. My story's the same as the OP's, so I'm going to experiment with the lower pressures.

MarsRedCLK

I did the same and echo your experience. Slightly better ride but to my ears, the Michelin have more tire noise and the Pirellis felt crisper turning, obviously related to stiffer sidewalls. I also run lower pressures than recommended and ride is decent.

Sailorlite

Didn't think of this earlier, but the OP's pressures are based on recommendations for a rear wheel drive car whereas the C43 is all-wheel drive. So what I'd really like here is AMG's official recommendation for non-run flats in an AWD sedan.

Nevertheless I'm just going to lower the pressures and see what happens.

Seanhfx

I've had these tires for 25,000+kms and 3.5 years, I can't imagine going that low as I've been at 36/33 the entire time.

////AMG_C43

​​​​​​It’s totally your choice.

I came to this conclusion based on the fact that these tires are closer to the C63’s PS4’s than they are to the factory performance run-flats. A few points to consider:


1) The sidewall heights on the C43 are equal to or greater than those of the 63S.

2) The C63S weighs roughly 100 lbs. more than a C43.

3) I have monitored both tire temperatures and pressure changes and see no issues. Only better.

4) I have also measured tread face temperatures after a mountain run. No issues.

5) I marked my sidewalls and checked for roll-under during hard cornering. No issues.

The car retains its turn-in characteristics but no longer shudders as the front tires move towards understeer during hard cornering


My car is not a daily driver, it was purchased as a winter time backup for our Porsche during cross-country drives. I live on a mountain and have great mountain roads to aggressively drive these cars on. If you are a freeway cruiser, stock pressures work and your MPG will be better.

In the end, the car rides better with no measurable downsides that I can discern.

As I said earlier, YMMV.