The tire pressure listed on the tire information sticker (inside the front door) shows a tire pressure of 42/43 psi. This also seems to be the pressure that the tire pressure monitoring system is set at. However, inside the gas filler door, the tire pressure is shown as 32 psi. Why the difference and which should I be using? When I purchased the car, the tires were roughly 40 psi, and that’s what I’ve used. Should I reduce the pressure to 33 psi?

 

My dealer, after service, always sets my S550 Coupe at 41 psi. I have found, after trying different pressures, that 33 F and 35 R seem best for me. So that's what I reset them to. You might want to try different pressures and find what works best.

 

Follow the fuel door. I run mine about 32 F and R, AMG 19s.

 

You can get pretty particular about this if you want. The fuel door lists factors such as how many people are in the car and type of tire and how fast you will be going. I tend to run around 41PSI front and rear with Michelin Pilot Sport 4AS+ tires on 20" staggered AMG Forged wheels on my S63 and is it a perfect blend of performance and all weather traction.

 

The door placard on US-spec vehicles only lists the so-called max load tire pressure. The tire pressure determines how much weight a tire can carry. Every tire has a load rating, that's how much weight it can carry at the max pressure listed on the tire's sidewall. Usually around 50 psi. At lower tire pressure the tire's load capacity decreases linearly, so the correct tire pressure to use depends on how heavy the car is at the moment, factoring in the number of passengers and cargo. Therefore, every car generally has at least two recommended tire pressures. The so-called normal load tire pressure and max load tire pressure. In case of MB, these are listed on the sticker inside of the fuel door on US-spec vehicles. You should pick the pressure based on your load scenario. Unless you load up the car with the maximum number of passengers and cargo, you wanna use the lower normal load pressure.

In addition, there is usually an additional set of recommended pressures for high speeds. The faster you drive, the larger the forces acting on the tires, so to cope with that, the tire pressure needs to be increased for prolonged driving at higher speeds. Depending on the model this may be for speeds above 100 mph or 155 mph. For reference below is the sticker from my AMG, which has quite a range of different pressures depending on the tires, load and speed. Just to give you an idea how complex this can get. For normal cars there are generally two recommended pressures plus a nominal increase for speeds above 100 mph.

Having said that, you can always use what it says on the door placard. That's the safest pressure to use if you don't wanna think about how much you have loaded up the car with. The reason it only shows the max load pressure goes back to the 90s when Firestone had a major issue with tread separation on mostly SUV tires, and some people died, because they were driving around with pressure too low for the load, so the tires overheated and the tread separated. The US DOT determined that Americans have no clue about tire pressures, so they mandated that only the max load pressure is shown on the door placard. The downside of using the max load pressure is a compromised ride quality if the car isn't loaded fully with passengers and cargo. That's the price you pay if you don't understand tire pressures.

The last thing most people don't understand is that temperature affects the tire pressures. Every 10F change in temperature causes a corresponding 1 psi change in tire pressure. So a) you must check your tire pressure when the tires are cold. Let them cool down in the shade for at least 3 hours, and not drive more than a mile before checking them, and b) if you have large swings in ambient temperature, then you need to check and adjust the tire pressure whenever the outside temperatures change significantly like summer to winter or a hot day and then next day cools down.

Also, after adjusting the tire pressure, you must reset TPMS, so it stores the new reference pressures. That's done by going to the Service menu, then Tires.

 

My car has 19" staggered AMG wheels on Michelins, and I tried ranges from 30 PSI - 35 PSI. I found that a cold tire with 34 PSI is best for me, my comfort level, and performance expectations. If I don't request in advance that the tire pressure be left alone, my dealer will always change the pressure to 32 PSI.

 

I follow the numbers on the fuel filler door and enjoy a good balance of gas mileage, ride and handling. As mentioned, whenever you do air up your tires, make sure to set them all equal and then refresh the TPMS system so you don't get a lot of tire pressure warnings.

Interesting to learn why a second, apparently conflicting set of pressures are shown on door labels. Figured it had to be some kind of government mandate.

 

You can ALWAYS determine the OPTIMUM tire pressure for the way you drive it.

It takes this thing called a "probe tipped tire pyrometer".

You take 3 readings across the surface of the tire immediately after a drive.
This information tells you::
a) if the tire pressure is correct {Tmiddle = ( Touter+Tinner ) / 2}
b) if the camber is correct {Tinner = 10º hotter than Touter}
c) if the caster is correct {forgot equations}
d) if the toe is correct. {Trear = Tfront}

All for about $100 that will save you thousands over your driving life.
You can find suspension problems before they show up as tire wear.

 

and where does this tire temp info come from?

I mean would not tire composition, rubber compounds tread pattern, tread depth, road surface and probably a dozen or so other variable have a huge impact on tread temps?

 

FYI: There is no right or wrong tire pressure for the vehicle as long as you are within the reasonable "acceptable" range (i.e.: 30 to 45 PSI ). Most manufacturers chose their recommended tires based on targeting less emissions for the US and are all biased towards higher values than really needed which scarifies comfort.

I found the most comfortable setting yet with reasonable balance between fuel economy as well as minimal tire wear and tear to be ~34-35 PSI Front and Rear (that's what am using for my 19" AMG wheels on the S560)

Keep in mind, the closer you are to low 30s PSI, the more risk you have for tire wear on the sides. The closer you are beyond the 44 PSI the more risk you have for tire wear in the middle. Hence, again, I think the 34-36 PSI offers the best balance between protection/fuel/comfort.

 

That is totally correct, hence why in other world markets you see them reccomend lower pressures than they do here.

How are your DWS06+ doing? Mine is in right now having the fronts replaced (I have the Pirelli PZero AS+) after 14k miles, they are BALD. Not happy about that.

 

I would disagree with that. The pressure needs to be correct based on the load of the car. Just driving around mostly by yourself I would agree with your statement, but if your car is loaded to the brim, you better stay with the recommended max load tire pressure or you risk overheated tires and/or tire failure.

 

They're still doing great. I've only put about 2-3K on them so it's too early to tell but they still perform well and most importantly are too quite. 14K for the PZero AS+ seems too low!! I wonder if it's related to temperature in your area...

 

Yes, I don't disagree. it goes without saying that if the car is fully loaded to the brim then you'd need to be closer to the upper range of acceptable PSIs. Having said that, for the 19" AMG, the 36PSI pressure values I recommended are not too far off from factory numbers either.

BMW vehicles has a live recommended tire pressure values on the screen that dynamically change and adjust based on the live/exact/current conditions (basically temperature). Wish Mbenz has that instead of us trying to estimate what does Cold Tire Pressure value mean when it's 0F or 50F outside (both are cold, but between the two, the pressure changes by at least 2-3 PSI!)

 

I thing the rubber compound is just soft, and not being able to rotate them they wore out quick at the outside shoulder. The rears look perfect, 7/32nds but the fronts were down to 3/32nds and they were completely bald at the outside corner. I would have gone to the DWS if I was going to replace all 4.

Fronts:



Rears:

 

Wow.. front ones look really bad. Do you think by the time the rear ones will wear out that the front ones would be ready again to be replaced? This way next time you can try the DWS. By then I at least would have served as a mature beta tester for the DWS on an S-class heavy vehicle and will continue to report. I drive the S-class less than 10K miles a year by the way, so still way to go, and I also swap to winter tires so it might take me 3.5 years to get to the 20K miles mark on the DWS.

 

I would imagine the rears have at least 14k miles left in them, and the front will likely be dead again. At that point I will have either traded the car or I will have bought it out and I will try the DWS

Pirellis have soft compounds, thats part of why I like them because they are quiet and ride great. Not being able to rotate them is just really not good for them IMO.

 

Absolutely, and all of the things you list, and a few your didn't, cause the optimal tire pressure to change.

The data comes from any book on race car setup.
Lets face it, your tires are the only point of the car that touches the road, and thus the only part of the car than can exert forces to move the car hither and yon.

 

I bought a 2020 S560 with 20" inch Amg wheels with runflats . When doing the test drive the ride was firm but at the time I thought it would be okay to live with. Boy was I wrong. The ride quality was so bad that I honestly contemplated trading in the car as an S class should not have such a bad ride. I came across this thread and replaced those horrible runflats with Michelin Pilot sport AS4+, and used your recommened 34- 36 psi.This is a totally different car . Everything is perfect . The ride quality and even the perfomance ( I do not drive my S class like it's a C class ) so for me this is the perfect balance. What a huge difference tires and tire pressure makes. .

 

It does make a huge difference. I run 19 inch Pirelli P7s, a luxury tire, at 33 - 34 PSI and the ride is so nice I can leave the suspension in 'sport mode' 100% of the time.

 

Honestly I am amazed at how much of a difference it makes. I also occasionally run the car in sport and it's still comfortable and luxurious .

 

‘S’ SERIES IS A HEAVY VEHICLE - YET OEM EVEN PERFORMANCE AMG THERE IS NO FRONT CAMBER OR CASTER ALONG WITH NO REAR CAMBER ADJUSTMENT - ALLOWING TO ADJUST TIRE CONTACT ANGLES SPREAD LOAD MORE EVENLY !

YET ESSENTIAL TO PREVENT COSTLY PREMATURE TIRE REPLACEMENT

A RESULT OF DAY TO DAY COMMUTING - Encountering high cambered roads with excess passengers side edge wear. Wheel squat Camber change through extra passenger loads. Fitting wide profile tires. No longer ongoing adjustment capability for curb knock damage. Or lowering vehicle height for performance / improved handling.

NOW “ONE ONLY CAMBER SETTING” - TO SUIT “SHOWROOM HEIGHT” CONDITIONS !

The often quoted reassuring “FULL FRONT & REAR ‘4’ WHEEL ALIGNMENT” - is now only adjusting Front and Rear TOE “directional” adjustment (New car industry’s best kept secret).

WHY - BECAUSE OF EVER INCREASING SPEED OF NEW CAR ASSEMBLY LINES - STOPPING TO ADJUST CAMBER IS NO LONGER AN OPTION. ONUS NOW BACK ON OWNERS TO FUND PREMATURE TIRE REPLACEMENT

DEALERS NOTING, AGREEING RE THE EXCESS EDGE WEAR - but only can offer, try and placate by stating - Alignment is within the factory (broad) specs.

WE SAW THE NEED THEREFORE AND MANUFACTURE FRONT AND REAR BOLT-ON KITS (designed so no special tools required or need for arm removal to install).

FRONT KITS PRICED FROM $480

SEE SPOILER (IT’S NOT A TIRE BRAND ISSUE) - RE ESTABLISH “CAMBER” ADJUSTMENT !






AUDI to VOLVO - K-MAC Experience Of Resolving OEM Suspension Shortcomings (and Costs) Since 1964 !

 

Alignment issue.

 

Alignment was totally within spec

 

What are your corner weights ??