Hi all.

Lurked a lot of the threads regarding tire sizing and ride in anticipation of my tires dying. Well, it happened a lot sooner than I thought. Fronts corded on the innermost edge almost in the sidewall. I've been running aggressive aligments on my track cars for a long time and I've never seen anything like this on a stock car. I had the alignment done while the car was in for the tire swap and they said the front toe was a ways off so hopefully that helps a bit. They confirmed camber as largely non-adjustable.

After weighing the pros and cons of tire sizing and not wanting any rubbing or drama, I opted for the safe bet of 255/275 Michelin PS4S's on my sedan. I've run Super Sports and Sport Cup 1's and 2's so I had an idea that these would be a big improvement. FWIW, Cup 2's are by far my favorite tire for regular tracking.

Car came back from the tire shop with pressures set near the moon which is what the door jam recommends. Not sure why other than possibly the weight of the car. Within a few minutes of driving, pressures had already exceeded maximum recommended sidewall pressure of 50psi. I bled a ton off and am now playing with ideal hot/cold pressures. I'm guessing I will land in the mid 30's cold. What a difference! Ride quality is MUCH better. The softer rubber seems to take the edge off bad pavement. As far as traction goes, I could never floor the car without tire spin drama. Between the increased grip and size of the 4S's, the car hooks up solidly almost all the time. There is now a just a little squirm on cold pavement but otherwise, the car just goes.

If you want a simple conservative upsizing that really benefits the car, 255/275 really makes a nice difference. FWIW, this is an otherwise stock car.

 

I just had the exact same experience... My front driver's blew because of the inner tire wear due to the stock negative camber... Switched to Michelin Pilot Sport 4S 255/35/19F and 275/35/19R and night and day difference. Even when I floor it in 1st, barely getting any slippage (given these are brand new tires).

 

 

No not really... I think the difference in performance is mostly attributed to the new tire compound rather than the actual width -- it's only a 10 mm difference... You won't see that change either ,stance wise...

 

Chris I did the same as you and I think not only do they have better traction but are quieter and ride better. I use 38 lbs front and 33 rear as the chart on the gas door recommends. Every time I go into the dealer to have service they put the pressure up to the door jam numbers and I have to re do them. They say MB put the higher numbers on the jam so they can use higher pressure for better EPA mileage numbers.

 

RDOCA good advice. Just actually noticed the numbers in the fuel door when I filled up last night. Going to try that. The super high pressures in the door jam are nuts.

 

Chris, thanks for putting this out there. I just bought a '17 C 63 AMG sedan and the stock super sports will be due a change soon! Having had an M3 and F10 M5 more recently, the first (and only negative) thing I noticed in comparison to those two cars was the lack of traction off the line. I will bleed off some of that factory recommended pressure which will hopefully help but beyond that, having read this thread I plan to replace with the slightly wider (A first for me since I always went with the stock size to match the rim width in the past) PS4S's. Thanks again for taking the time to post, Jason

 

What were your original tires? I have ContiSport 5p and same experience of front tires cording on the innermost edge. Had to replace the fronts. Read some article on Continental Tires website, they recommend to up the pressure when doing a lot of highway driving. This I did as I went for a long trip to US. Now I have the car in Europe where it'll be driven mostly on curvy country roads and I expect more balanced wear. I will still keep the pressure high as I am only 150 km from Bavaria where I can drive with no speed limit on autobahns.

BTW I had alignment / toe checked and adjusted at two different MB shops. They were slightly out of spec, but I suspect it's the camber which can't be changed. My fronts are 255/35 R19, rears 285/30 R19, both from factory.

 

Other than the additional 10 mm difference in extra width, which has to help a tad in grip. What is the difference between Pilot Super Sport and the Michelin PS4S?

 

The PS4S is 6-year newer technology and is the replacement for the Super Sports.

Going with the PS4S over the PSS is a no-brainer.

 

Haha - exactly. After I posted, my lazy a** looked it up. Should have done that in the first place.

 

 

 

Here's a simple before after test:
- Before on Dunlop OE size SportMaxx: from a complete stop, mash the throttle; watch traction control light flicker; feel rear end squirm and lose traction; repeat with same result
- After on larger Michelin PS4S: same exercise except no traction control light and the car just hooks up, accelerates and goes straight; repeat with same result
- Conclusion: more grip; some due to better tires; some due to width. Would have to repeat exercise with OE size PS4S to know the exact attribution.

The difference is real and quantifiable for me. YMMV.

 

 

 

What are your rear tire pressure's at?

 

What did you find works best on the rear for the PS4S?

 

 

I set mine for 33 cold in the rear as well. I try to set them for 33 based on the prevailing temperature for that time of the season.

For optimal traction off the line, it's better to go a little lower, so I error on the side of being a slightly low than too high.

If you do a lot of high speed highway driving, you'll want to error on the high side.

 

Ditto

 

Just wanted to chime in: my original PSS's are finally done at ~24k.I am replacing with the 4S. While shopping around, I noticed something: the 255/35 and 275/35 4S are actually CHEAPER than the narrower OEM size by about $50 total (at least at Tire Rack). So if anyone is not convinced on the performance benefits, get the wider tires just for the cost savings alone!

 

Thanks,

i also noticed the wider tires tires were cheaper and when talking to discount tire on the phone , I was offered a further $120 discount if I bought all 4 without even asking for it!

Jason

 

Interesting...do you recall who you spoke to? I didn't actually order them yet, and wouldn't mind saving $120...

 

Hi I put these on my c63 2017 sedan. What pressures are you using?