carson2

First off, this is not trying to start ANOTHER thread on tire preference...that's been beat to death by now. I contacted michelin on when the Pilot Sport 4S would be available for our cars, and the response I received was: "We do not have the rear available. From what I can see we do not plan on releasing the rears within this year. We do offer a 305/25R21."

So my question is does anyone have experience in using the narrower sidewall? Granted 305/25R21 vs 305/30R21 isn't much difference, but its a pretty good percentage shallower sidewall, which I would think would create a few downsides (harsher ride, noisier, and greater probability of pinch flats) - though I'm unsure to what degree I'd notice those. So the question is this - do those trade-offs outweigh the handling/noise/other benefits of the Michelin PS 4S (which have been my go-to in the past)? Thoughts?

detansinn

I am going to buy my time with the Pirelli Pzeros and wait until the proper Michelin fitment is available.

carson2

Respect your opinion detansinn, so can you qualify that? For example, if your PZeros give up the ghost before the proper Michelin fitment is available, do you go with Goodyears, or do you go with the standard front Pilot 4S + 25 series rear?

detansinn

Thanks. 👍

With the pandemic, I don’t expect to burn through the PZeros any time soon. Like many residents living in “stay at home” states, I am putting hardly any miles on the car. I figure that the winter set will be back on the car before I make much of a dent in the tread of the PZeros. ☹️

By next summer, Michelin will have a proper fitment that works. I will probably treat myself to a set early, because I will be making up for lost time.

I originally planned a coast to coast trip this summer, but the pandemic derailed those plans. I might as well do it on Michelins. 👍

Michigan 992

All of the quoted sidewall dimensions are approximate. You can get a better feel for what you are asking by comparing the Porsche approved actual tire diameters versus any other sets you are thinking about. I haven’t bothered to do this yet. I just want this year out of my Goodyear’s and then there should be several good options on the market.

uniqueMR

Proper Michelin fitment is a must.
F: 235/40-19 & R: 295/35-20 OR F: 245/35-20 & R: 305/30-21

diononiz

I had considered using the 315/30/21 but they seem to be "Mercedes" branded. Any thoughts on this size? It would put more contact patch on the rears.

Dan Nagy

I would opt for patience until the proper tire is ready.

DallasVP17

Why not go wider? I’m going 255/35R20 fronts and 315/30R21 rears with the PS4’s when my car arrives later this year.

uniqueMR

Will it fit if going with 255s & 315s?

DallasVP17

Yes, it’s only .39” wider, 0.195” per side.

carson2

If only .4" wider per tire, what is the downside? Getting back to the purpose of the OP's post (me) - I really like the Pilot Sport 4S, and given that they won't be available until sometime in 2021, I'm pretty sure I don't want to buy another set of PZeros or Goodyears... so what is the best pro/con balance of either slightly lower profile (25 vs 30 series), or slightly wider tires? Kind of like the wider suggestion as it doesn't compromise much in terms of noise or ride harshness vs. a narrower sidewall...but why wouldn't the Michelin tech have suggested the possibility?

DallasVP17

I think you already know the cons of the lower profile choice, you said "noise or ride harshness vs. a narrower sidewall" and I cannot think of any pro's for it. For the 315's I think we need to investigate 1. Weight 2. Tire tread width, and 3. Being a Mercedes specific tire, if it has any other specs that are outside of the normal 315 sized tire. I just remembered that my M3 CS has BMW specific 285 Pilot Super Sports rear's and they have a different tread width and weight than the standard non-BMW specific Pilot Super Sport 285's. Since I plan to go 315's on mine too I am going to research this more tomorrow.

DallasVP17

After doing a little digging I discovered the following info. For the 315/30R21 PS4's the MO1 Mercedes designation is a stamping on the sidewall indicating that the tire was used on and approved for Mercedes vehicles. Basically, Mercedes and Michelin got together, took the 4S, and tweaked it for use on the newer AMG GT 63. They did not publish what tweaks were made, they just put a new part number and the stamping on the sidewall. As you may know, Porsche does the same thing, so your current tires should have NA0 on the sidewall. The issue is we do not know what, if anything, Mercedes tweaked on the tire when they made it MO1 spec, so we don't know if there could be inconsistencies in traction, handling, or ride when running on the 911.

In other words, do not get this wider tire that is a Mercedes spec. The best thing to do is get a Porsche spec tire, at this time your options are Pirelli P Zero (PZ4), or the GoodYear's. I did find out that Michelin is supposedly in the process of developing the the PS4's with Porsche at this time. However, there is no ETA for release, especially with the Corona virus.

So, we'll have to wait for the PS4's to be released, or get a currently available Porsche spec tire.

Wish I had a better solution.

JesseRohr

I had that size on my GT63 Benz before I snagged my 992. Great tire. I would have zero issues using a tire that is NOT designated specifically for a Porsche. I have almost always put high quality aftermarket wheels and tires on my cars including my supercars. I have never had issues and it's comical when I read things on these forums suggesting only manufacturer specified tires are suitable for any car. I work in the automotive aftermarket industry and have many friends in the tire space. Believing there is some special deviation from the traditional manufacturing process for these tires for any car manufacturer seems silly.