superswiss

Before you get excited, unfortunately the new S 5 is OEM only for now. It's not the replacement for the aftermarket 4S yet. That according to Michelin is not planned until midcycle. Exciting to see that the new S 5 is picking up things from the Cup 2 and the BMW Star 4S. So I guess for now I might still go for the BMW Star 4S if I can source it next time I need to replace tires.

L8apexer

The Mercedes-spec PS4S MO1 is readily available on Tirerack right now, and has been for months. I snagged a set of rears a while back even though I didn't need them until 5000 miles later. They were very hard to get a few years back.

superswiss

That must be for the sedan. For the coupe with 19/20 there's no MO1 PS4S on Tirerack, but they have the Blackwall and Star BMW in stock in the coupe sizes. The only MO1 for the coupe on Tirerack is currently the PSS.

japamg

Whats the difference between MO1 and standard PS4S? Or is just the homologation?

thanks

W205C43PFL

I believe the MB original ones were tested by MB themselves, I heard there are other differences but minor, I wish I can find that thread I read comparing OE and aftermarket of the same tire model, sorry about that. If I do come across it I will edit this post.

untamedd

this must be trivial because i highly doubt your average driver is gonna notice any difference between a standard tire and mo1 of same tire model

japamg

Agree

Not sure if there is any aesthetic difference

W205C43PFL

Actually looks like it might be more than that, I couldn't find the thread I came across before when a forum member actually rip apart and compared the composition of the tires, the tread depth, the tread pattern, the extreme cold/heat differences, they did their own research and concluded the tires having minor differences at least for MBs (it might had changed now or it might not).
MO1 as you know is designed for AMG vehicles
MOE is Mercedes-Original Extended (so some sort of run-flat)
MO is Mercedes-Original non run-flat
MOS is Mercedes-Original S-Class (so probably foam filled)

W205C43PFL

I found these thread instead which I am not sure if it is helpful at all: https://mbworld.org/forums/wheels-ti...-mercedes.html
https://mbworld.org/forums/gle-class...-mo-tiers.html
https://mbworld.org/forums/w213-amg/...-sport-4s.html

japamg

Thanks! Any info is helpful 👍🏻

superswiss

I'm assuming you watched the videos I posted in one of the threads linked by @W205C43PFL above. As said, the manufacturers tend to keep this information a closely regarded secret, but the specific differences that are laid out in the BMW video gives you an idea that they can be quite different in the compound makeup etc. to emphasis specific performance aspects, or improve on the base tire.

japamg

Yep watched the videos. So compound is the main difference. I was wondering if there were also aesthetics differences

superswiss

There can be. The Cup 2 for the AMG GT Black Series for example has an outline of the car on the sidewall, but for most there isn't an aesthetic difference. The differences are with the compound, internal tire construction and tread pattern.

user33

I once put a set of BMW homologated Cup 2 tires on the front of a C63 S sedan (couldn't get the MO tires then) and they were very prone to rolling over on the sidewall unless I ran them a few PSI higher than the MO Cup 2 tires in the same size on that car. I suspect the sidewall is stiffer because the BMW sedan (for which the tire was designed) is a few hundred pounds lighter than the AMG sedan.

superswiss

It is definitely not trivial. The car manufacturers spend a lot of time with the tire manufacturers to tune and optimize the tires to their vehicles. However, in this particular case I have to ask, did you make sure the load rating was the same on both tires? When going between standard, MO, BMW Star or whatever, you still have to make sure you stay with the same load rating. The OE tires for a lighter vehicle will have a lower load rating most likely, so they won't be suitable for a heavier vehicle unless you can compensate via the tire pressure as you did.

For example for the C63S coupe the load index front and rear is 96 and 99, respectively, and the second factor is the load range, XL in this case. You don't wanna put a standard load (SL) tire on a vehicle that requires XL tires, so make sure it's not just the size that matches, but also the load index, load range and speed rating when considering non-OE tires.

Lastly a word on tire pressure. Often overlooked and misunderstood. There have been some that advocate running higher pressures than recommended for better wheel protection, however with tires like the PS4S that uses a split compound that is not a good idea. The PS4S uses different compounds on the outer shoulder vs the inner shoulder. The outer shoulder provides dry grip and handling and the inner shoulder provides wet grip and handling. So when running higher psi than recommended for the current load of the vehicle, then the tire tends to bubble in the center lifting the shoulders up and reducing the contact patch. You may think that a couple of psi can't make that much of a difference, but I beg to differ. I can immediately tell if my tire pressure is not correct. The steering gets loose and light and the car just doesn't sit right on the road. For example I had new brakes installed the other day and forgot to remind my indy not to mess with my tire pressures. When I got the car back I could immediately tell that something wasn't right on the way home. Checked the cold pressure the next morning and all tires were 2-3 psi too high. After lowering it back down to the recommended pressure all was good again. FWIW, this is with the standard blackwall PS4S for now. The car handles and drives much better compared to the OE PSS with the same pressures.

Stoic_nihilist

What tire pressures are you running on your ps4s fronts and rears?
Thanks!

superswiss

For normal load 33f/32r as listed on the sticker inside of the fuel door.

user33

I agree with what you wrote.

In my case, the BMW homologated Cup 2 tire had the same ratings as the MO version and the pressures to which I referred were still within the hot running pressuress for the Cup 2 tires (this is all for on-track running ... fuel-door pressure used for street running, though I did swap wheels/tires to PS4S for non-track days).

It always amazes me that tire shops get the tire pressures incorrect when every MBZ I've owned has had the info on the fuel door. #;-(

Stoic_nihilist

Oh wow.
For the winter, I ran 43 fronts and 38 back on my 19 in OEM MPSP.
Blew out a front left tire when I hit a pot hole last week.
Replaced both fronts with 4s' but kept the super sports on the rears as I still have 5/10 tread wear.

I will make sure to lower the PSI so not to blow these again.

Audi_A3T

Hello,

One doubt, would the pressures on the sticker be valid for all tyre models or only for the original PSS MO1? For example, if you put PS4S instead of PSS. Maybe not all tyres work in the same way.

superswiss

It could be possible that you might have to adjust the pressure based on a specific tire model. Like the poster above mentioned that the BMW Cup 2 on of his non-BMW had a tendency to roll over the sidewall and he had to increase the tire pressure, but I would say that's rare. Keep in mind the C63S has several OE tires, but the sticker doesn't have separate pressures for them. The coupe can from the factory be optioned with Cup 2 tires for example, but the 19/20 inch recommended pressure doesn't change and the sticker lists the pressure for the 19 inch tires even if the car doesn't come with it and I believe there are a couple of different OE 19 inch tires as well.

Also, the recommended tire pressures are for street driving. On a track you'll have to deviate from them for example. You would actually lower the pressure for the track, because the tires reach much higher temperatures.

W205C43PFL

A video on it is out but it compares with the Cup 2 and not the PS4s