Goodbye Runflats! (Michelin Pilot Sport A/S 3+)
 

2018 C43 Sedan. After 20,000 miles on the stock Contintential Pro Contact (SSR) 18 inch runflats there is plenty of tread left for lease turn in, but I have had enough of the stiff ride and simply mediocre grip. These tires held up well but were no where near as good as the Pirelli Cinturado P7s that I had on my old C300 in terms of performance.

This weekend I am having Michelin Pilot Sport A/S 3+ non runflat all seasons put on. I really do not want to go to dedicated summer and winter tires. 2 year road hazard warranty from TireRack does not hurt either.

I will report back.

Looking forward to the report.

The stock 18" SSRs and their stiff sidewalls follow the crown of the road like nobody's business.

I'm not sure what that means. Is that bad? I think you mean they are harsh?

I have just purchased a certified c450 with a new set of the Pirelli c7's you referenced. It is my first kick with runflats and they are terrible..At 75/80 mph they seem to hum, and are very harsh..My previous car was a CTS-V that I had put A/S 3+ on and they were terrific tires..The CTS-V also had no spare so I just bought a goop kit and crossed my fingers..I expect to be doing the same very soon with these tires.

Awesome thank you!

Can you please post a picture of your A/S 3+ non run flat all seasons. I am curious to see how they look on the car (though I have 19'' rims).

https://cimg3.ibsrv.net/gimg/www.mbw...1cebf5dfb.jpeg
https://cimg9.ibsrv.net/gimg/www.mbw...ae88a2623.jpeg

Lowered on H&R sport springs...

I did the same back in January. Wouldn’t ever go back. For me the biggest differences are:

1. Grip. The PS3s have far more grip than the runflats
2. Steering Feel. Night and day. People don’t talk about this enough, but first time with them on you’ll see. It’s such a pleasure to drive now.
3. Ride. Ride is much more supple and doesn’t crash over bumps.
4. Braking distances. Much better. Byproduct of item 1 above.

Only downside is that these PS3s definitely have a bit more road noise than the stock tires.

OK so I just got the car back with the new tires. Michelin A/S 3+. Where to even begin?

Superior to the outgoing continental run flats in absolutely every way imaginable. Steering feels improved, noise reduced and I can hear the exhaust crackling and doing its thing even with the flaps close now.

Coincidentally I got to drive it a few minutes in the dry and then a rainstorm came in and flooded the highway. These tires are unflappable and cut through the water like a boat. I had a grin on my face.

The entire car feels more lively and more sports car like but at the same time all of the harshness that was bugging me is just plain gone. I had an E class loaner for a few hours and well I wouldn’t say this car has as comfortable a ride as that E300, this is a big step in that direction.

It feels like that center zone that sometimes can feel sort of vague when the wheels are turned like less than one degree now is giving me more subtle feedback as I move the wheel. I just feel like I have more control over the car and the car drives better in a rainstorm than it did in the dry with the run flats.

The only regret I have is not doing it sooner. You don’t have to drive it hard the difference is readily apparent in regular driving.

How many miles on the Conti's when you replaced them? What pressures are you running in the new A/S3+'s? Thanks.

About 21,000 on the Continentals. Probably had another 5,000 miles left.

I also had Pirelli P7 Cinturado 18 inch tires on a C300 with sport suspension, and it was the same crashy run flat feel.

They used lower pressures than they used for the continentals. The Continentals were always like closer to 40-42. That is per the gas cap placard and door jam.

On these, shop (dealer) only inflated to 32 ish, which I am not sure how they came up with. They test drove 2 miles so must be ok. Alignment was fine on Continentals just had car checked for Service B last week. Nevertheless, I let them do an alignment for the Michelins. Not sure if anything got adjusted but don’t care.

I have tried the runflats at lower pressures. It helps a bit to run them a little lower, but it isn’t transformative like these.

Thanks for the review! Glad you're liking them so far.

As far as the tire pressures are concerned, on the sedan, we're supposed to run 36 F and 35 R w/ all-season tires equipped. For summer tires, tire pressures of 40+ PSI are used on 18" wheels.

Was always curious what the coupe requires for the 18" setup with all-season tires.

Yeah I am really not sure if there is a new calculation for minimum tire pressure just because I went to a new tire. These are just first impressions I’m sure there will be some tweaking. I’ve run the continentals on the lower side and they were never as well mannered as these Michelins.

Does anyone know if there is a mathematical calculation based on the tires maximum inflation to determine the optimal inflation?

I just go to the inside of the gas cap for the optimal cold starting PSI.

Example:

My stock Conti RFTs have the M+S symbol on them. Gas cap on my sedan indicates for M+S-stamped tires: 36 (F); 35 (R).

Checked the gas cap of a C300 sedan, which has the same OEM Conti RFTs as the C43 sedan (when equipped with 18" wheels and all-season tires).

Cold starting PSI recommendation? 36 (F); 35 (R). My tires have worn perfectly using this approach, and the handling/ride has been as good as possible on the RFTs.

My dealer incorrectly had my tires at 41 PSI all around (based off of the door sill, which is the incorrect approach/number) at delivery, and the ride was terrible, the steering wheel was nervous and darty, etc.

I Yeah the thing is in my experience dealer does tend to over inflate a bit and I usually end up taking some air out but in this case they clearly put some thought into it because it feels awesome. I have a feeling there is a range they have to work with I know they test drove it supposedly for 2 miles. So maybe they tuned to feel a bit. It was clearly a very deliberate decision because it’s very consistent across all four tires and deviates significantly from the gas cap but the way the car was responding I could tell the car just liked the way this was set up.

I also was a minute or so underway when I checked the pressure meter so I’ll get a cold reading. I seriously doubt if they were under inflated they would’ve felt so sure footed.

I’m going to check up and make sure everything is optimal.

When I had my '13 C63, I initially got my summer/winter tire swaps done at an independent shop. I trusted that they set the tires at the proper PSI and my TPMS never went off so I thought all was well.

Turns out the tires were constantly underinflated, and that caused a severe case of tire cupping. The ear-piercing, resonant whine from the tires when leaving the shop one day was unreal. Ever since that experience, I've always paid obsessive attention to my pressures. Not only do I want to keep them consistent for best performance, but for even wear to promote life and prevent cupping.

When you replace the original equipment runflats with non-runflats, do the fuel cap pressure recommendations still apply? Wouldn't these different types of tire have different optimal pressures? I think all USA C43's come from the factory with runflat tires, but is there any market where 19" non-runflat tires are standard? If so, what's the pressure recommendation there?

I’ve been researching these tires as well and after reading these comments I pulled the trigger and purchased a set from Costco. Is $785 installed a decent price? I’m sick of the road noise and harshness from the run flats.

Will/did you get a spare or getting the green goop and a compressor? If you found a spare can you provide any info?

785 is good considering I paid 1K about two years ago.
This was also at Costco.

The installer told me that those goop sealants can damage the TPMS and recommended not to use them. But I’m not sure how factual that is.

The Slime sealant says emphatically that it's safe for the TPMS sensors. Last month, in rural TX, we repaired a flat on a Porsche using the factory Porsche flat tire kit - sealant and compressor. The sealant worked well enough to drive 50 miles to a tire repair place, where they dismounted the tire, washed out the sealant with water, patched the tire, and remounted the tire. The TPMS sensor never noticed - continued to work fine.

So I'm sold on the sealant and compressor for emergency tire repair. I previously thought that the sealant would ruin the tire and the sensor - but that's not the case.

Good to know. Thanks.

On the expressway into work today, I would say ride is on the firm side. The crash is gone from the runflats, but these are firm tires. For a super luxurious ride, there are probably touring tires more suited for that.

I am investigating tire pressures. I got 34 cold when I started up this morning, so I am looking to whether a few more pounds should be added. They do handle really well. I will post more findings at like 500 miles. (two weeks?)

Pressure will increase 4 to 5 lbs after about 10 miles of driving.I set mine to 34 cold and they usually stabilize at 39 lbs after a few miles of driving.

For the record, here are the Mercedes fuel flap pressure recommendations:

18" - 42/33 F/R
19" - 36/33 F/R

These pressures are for runflat tires, lightly loaded and measured cold. Cold means 20C or 68F.

After driving a very few miles the tires will warm up regardless of the weather and the pressures will increase. Mercedes certainly knows this and sets their cold recommendations accordingly.

And to throw even more uncertainty in the mix, this is off of the Michelin website:


Original equipment vehicle tire size:
Front: 225/45R18/XL 95Y
Rear: 245/40R18/XL 97Y
Recommended Tire Pressure, PSI
Front: 39 / Rear: 45