Oh ok... I think then changing tires would be the best bet. Run Flats have notoriously been known for running pretty harsh and wearing quite fast. Also I am assuming that you are running 18's. So I would get something that is not a high performance tire. They tend to be very grippy and run quite hard as well. The previous poster suggested letting the air out to 34/35 I think it was, I would try that, but sure to check your wear pattern, that could affect your camber and you will have to get an alignment done regularly if the tires are not well inflated, and also affect fuel efficiency. I would start at 36 psi and work my way down, but wouldn't go lower than 32 to be honest. Hope this helps

 

Anyone picking up their cars should make sure to check their tire pressures. For example, I found mine to be over-inflated to 53 fronts, 57 rears according to the sensors! I almost find that hard to believe. I wonder if they were over-inflated for shipping purposes. I have not driven the car since driving it home from the dealership, but I'll need to make sure to test the pressures with an actual gauge before heading out next time.


Note:
(yes, I realize that I am from New England and I am talking about going out and purposefully deflating things)

 

I have owned many vehicles in my lifetime and have always followed pressure recommendations on the door jambs or any location they may be located. I was advised by several mechanics this is what you follow, not the pressures shown on the tires themselves. I would find it odd that Mercedes would not follow suit. That being said this is my first experience with run flat tires and thought the pressures seemed very high. The dealer had the pressure at 35 at all corners. I inflated the tires to the recommended pressure on the door jamb. I did not notice a major difference in the ride since run flats have a horrible ride to begin with. So what's the deal with Mercedes? Follow the door jamb or not???

 

Now that both my dealer and I have spent 4 months in this car, I have had some time to play around with tire pressures. I have used both the OEM 18" RFT Continentals, and 18" Goodyear snow tires. The Conti 18's are staggered, while the snow tires are 225x45x18 all around.

On both sets of tires, I have gone as low as 34 psi all around and as high as 43 psi on the rear tires. On the Contis, I have noticed minimal change in ride quality regardless of tire pressure. That was surprising. With the snow tires, which are not RFT's, there was slight improvement in ride with lower pressures. Handling did not seem dramatically different either way.

I spent two weeks running the snows at 34 psi all around, then went to 38 psi all around. The car actually felt better at 38, so that's where I'll keep them. These are all cold tire pressures.

Fuel economy seemed a bit better with the higher pressure, but that's not a surprise.

The only conclusion I can reach is that tire pressure is not critical with this car. With my Porsche, every couple of pounds changes the handling and ride characteristics ... with this car the changes are very subtle.

 

i just picked up my car yesterday and the tire pressure was 44, 47, 46, 45
is this normal? or is it too much?

 

Congrats on your new car. Exciting! Those pressures if taken when wheels are cool are high unless running full load and consistent high speed.

 

The programming instructions in our manual for the garage door opener were wrong. Had not been updated from previous model. MB tech came to the house and programmed it. Said the manual was incorrect. Things do happen.

 

Mercedes decided to put their recommended tire pressures on the inside of the gas filler door. They also put another set of pressures on the driver side door jamb which is where most manufacturers put them. The actual pressure should be 36psi all around when the tire is cold. The pressures on the door jamb are for when your carrying a heavy load. Whoever prepped your car went with the wrong sticker. I unfortunately drove my car for about 1500 miles with overinflated tires and a very stiff ride before I figured it out.

 

I have the same door jamb and gas flap stickers as bacardi73. (I especially appreciate that remark on the gas flap, "For driving less than 100 mph: -4 psi"! Are there any places in the U.S., even in the West, where speeds of 100 mph can be sustained?) I have a C3004MATIC Luxury with the standard 17" wheels and 225/20 Pirelli P7 MOE (Mercedes Original Equipment) tires. (MOE tires are the product of Mercedes partnerships with several tire manufactures to produce run-flat tires with better riding and handling. However, MOE tires have lower limits of allowed speed and mileage when flat. If the car is fully loaded, these limits are MUCH less.)

When delivered in early Feb., my C300 had tire pressures from 37 to 40 lbs. The on-board TPMS system agreed exactly with my dial pressure gauge. The ride was much stiffer than my previous 2007 C2804MATIC Luxury. That car had 16" 205/55 Michelin Pilot Exalto A/S tires. Perhaps because they were at least 80% worn, they rode very well.

Yet, contrary to all other commenters, I believe my Pirellis now ride at least as well as the Michelins did! I say this because I am comparing only those aspects of ride for which I consider tires directly responsible. I am referring to the effect of broken surfaces, with patches, tar strips, and so on. On these surfaces, the Pirellis absorb the roughness quietly and smoothly.

Where my C300 comes up short is on wavy surfaces, frost heaves, and other undulations in the pavement, even where the pavement is not broken. These set the whole car in motion, giving a jiggly ride. The car does not bounce; it really follows the road surface too well. The effect is more sporty than the ride of the C280, but less comfortable. This I consider the effect of the suspension, not the tires.

After reflecting that I was unlikely to do any cruising at 100+ mph(!), I reduced the tire pressures in steps to 32 psi front and 34 psi rear. That is what was recommended for my C280, and that is what I used. Yes, the recommended pressure for the rear tires was slightly higher than for the front. However, shortly before I traded it in, the manager of the independent shop where I had my C280 serviced told me that the shoulders of my tires were wearing excessively. That meant under-inflation; I certainly don't challenge curves. I will either keep an eye on the wear patterns or, more likely, run 34 psi all around.

Using 32/34 as tire pressure has made a slight improvement. The car now jumps around a little less. I am not an engineer, but I think this is because the softer tires transfer less energy to the suspension. On all of my previous cars, slight over-inflation improved the ride. I reasoned that the tires were transferring more energy to the suspension. The suspension dissipates energy as heat from the shock absorbers. The tires dissipate less energy; they merely release it elsewhere, including back to the road. The timing of this release matters a lot, cushioning or reinforcing impacts and exciting or dampening resonances.

 

I'm going with 33/35. Seems soft but well controlled. I'll watch for tire wear.

 

Anybody have any updates on the affect of changing tire pressures?

I just upped my pressure from 33 (started in summer at 36, but it's colder now) to 37 front/38 rear. Haven't driven much yet on it, but it seems a bit more harsh (base steel suspension on 18 in runflats). Since I don't EVER get above 100 mph am I running pressures too high?

Also, has anyone noticed whether gas mileage improves with higher pressures?

Thanks