MCF

What are you guys running? I am at 33 in the front and 36 in the back, but based on driver door sticker it should be closer to 36 front and 40 back (cold). That seems pretty high. This is on a 2011 luxury model. Thanks!

CEB

What makes you think that is high? The 350 isn't a light car.

I would start with the factory settings and adjust from there. I've always found factory settings to be a bit on the low side as the manufacturer needs to walk a fine line between handling, tire wear and comfort.

Mbenz260e

I need to adjust mine. They are about 37 all around now cold but I usually have my backs at 40 cold. Had new tires put on and dealer put them all the same. 33/36 sounds low to me but probably makes it more comfortable?

I am a 2012 luxury diesel...

CEB

In my experience - and this is after a zillion cars and an equal amount of miles (I just found a certificate for a safe driving award for 500k miles - in my assigned staff cars - one of which was a Chevy Cavalier wagon - in Europe), the factory recommended settings are low.

I set my tires to the factory settings and drive for a week. Then I bump them up by about 3 psi and drive for another week. If my teeth haven't been jarred from my mouth then I leave it there.

By law, the TPMS sensors must alert at 25% under the required pressure, so if the recommended pressure is 40psi, then the sensors will alert around 30psi. 15-20% under the recommended pressure will lead to increased tire wear and more than 25% can become dangerous. Around 30% or so low and the pressure becomes critical, possibly causing internal (invisible) tire damage.

Knock on wood, but I've also never had a catastrophic tire failure - although I've had my slow leaks and nails - in part because I check pressure and tire condition frequently and change my tires at 4/32nds.

telemakhos

Just make sure you pay attention to the difference between the pressure for maximum load vs normal load. Sometimes the numbers on the door/pillar placard vs the inside the gas filler cap are one of the other. I find that a little bit above the normal load pressure gives me the handling I want.

listerone

I do 36 front...38 rear.

samkimg

Staggered 18's with 36 front and 41 rear seem to keep me glued to the road.

BenzV12

Front : 38
Rear : 42
I do run 17" wheels ,most guys say these are too high for a car but I show them what says on the fuel door lol

mbuster25

I'm set at 34 front / 38 rear on 17s contis on 350 4matic

greasykid

I have 11,000 mi on my W212 Sport 2 wheel. Check my tread wear regularly with gauge. Have 34 lbs cold front & rear. Wear is even all around. Tried 2/3 lbs more, did not notice any diff except a harder ride. This is my third W212 with the same results.

Regarding TPM. I disagree with above comments. The TPM is not set for any exact tire pressure. (i.e.40 lbs). Put in whatever tire pressure you want. You then need to ACTIVATE the TPM at that pressure. Low pressure warning system will take over from there. Any time you change tire pressures the TPM must be reset to that new pressure. This is done from the steering wheel buttons. If all else fails read the book! If you do not reset, then the TPM will react to the last reset pressure.

CEB

And how is that different from what I wrote? If you set it to the recommended 40psi then it will alert at 30 (at a minimum - most likely around 32)

GoBlando

The entire weight of your car, passengers, and luggage is supported by your tire pressure. Are the 17" wheels and tires standard on your car? If so, then do what the gas filler door says. Don't run the same weight in all the tires unless the manufacturer says so or you know what you are doing for specific handling dynamic reasons. This is a Mercedes, not a chevy. They actually tell you what is best for a balance of safety/comfort/performance (probably more on the safe side). Also, cold is a big deal especially with low profile tires. Search my other posts for directions to properly fill your tires.

In my old S5 it recommended 39 psi front and 36 psi rear. All 4 tires were the same size (255/35/19). The weight distribution of the car required more pressure in the front to prevent the tires from deforming differently than the tires in the rear. 39 all around was too harsh and tail happy, 36 all around was too sloppy in the corners. I tried higher and lower, different ratios, but the car always felt best at 39f/36r COLD pressure. I found in 5 years of ownership that even when I went from the summer tires to 225/45/18 tires for winter, that the car felt best at these pressures.

For reference:
Pressure of a Gas = (amount of gas * Gas Constant * Temperature) / Volume.

greasykid

[QUOTE=GoBlando;5676166]The entire weight of your car, passengers, and luggage is supported by your tire pressure. Are the 17" wheels and tires standard on your car? If so, then do what the gas filler door says. Don't run the same weight in all the tires unless the manufacturer says so or you know what you are doing for specific handling dynamic reasons. This is a Mercedes, not a chevy. They actually tell you what is best for a balance of safety/comfort/performance (probably more on the safe side). Also, cold is a big deal especially with low profile tires. Search my other posts for directions to properly fill your tires.

In my old S5 it recommended 39 psi front and 36 psi rear. All 4 tires were the same size (255/35/19). The weight distribution of the car required more pressure in the front to prevent the tires from deforming differently than the tires in the rear. 39 all around was too harsh and tail happy, 36 all around was too sloppy in the corners. I tried higher and lower, different ratios, but the car always felt best at 39f/36r COLD pressure. I found in 5 years of ownership that even when I went from the summer tires to 225/45/18 tires for winter, that the car felt best at these pressures.

For reference:
Pressure of a Gas = (amount of gas * Gas Constant * Temperature) / Volume.[/QUOT

Have 18" tires. This is my 29th Mercedes over 40 yrs so I am reasonably familiar with the features of MB.I know the diff from a Chevy. Yes the filler door specs the same pressure all around. I stated what I do and have found what works for me. You are free to do what you want. I am not out to convert anyone. I am agreeable to listening to other views;but pls no lectures.

Arrie

I had my rear pressure set at around 36 psi with the Conti crap tires and they totally wore out in the middle. I put new tires on and keep pressure at around 33 psi and I'm trying to monitor the wear. Don't know yet how the wear is across the width of the tire.

I always drive with no load in the car and the 36 psi for the rear seems way too high.

CEB

3psi cannot make your tires wear unevenly. There is something else wrong

Arrie

Just to let you know 3 psi can make a big difference in how the tire wears.

But for curiosity, what would you think is wrong other than tire pressure when the rear tires both wear severely in the middle with no sign of other than normal wear at either inside or outside edge of the thread?

What would that "something else is wrong" be?

Six_Speed

Look on the inside of your gas cap door for the recommended tire pressure label. I don't know why MB have two labels.

El Cid

Have 17" wheels and run them at 32 and 37, which is two lbs. over lowest recommended. Running them at highest makes a much harsher ride. I do this for all my cars and always have.
One way to check is to periodically measure tread wear to make sure it is even.
My 2010 manual says use higher pressure for fully loaded or driving over 100 MPH!
Forget which way, but too much wear on inside and outside indicates either too low or too high a pressure.
Once you decide on a pressure, don't forget to reset TPMS.

Bigglen1

Increased center tread wear indicates OVER-inflation.
Increased outer tread wear (both sides) indicates UNDER-inflation.

Right CEB?

CEB

Interesting question because center wear is almost always caused by overinflation but - in general - "overinflation" is considered to be about 20% over the manufacturer's recommended ratings.

Remember that the psi recommendations on your door jamb are a compromise between handling (more psi is better) tire wear (more is better) and comfort (lower is better). On most luxury cars, the ride is weighted towards the comfort side so the sticker is actually below what it really should be.

In any case, 3psi will not show appreciable center wear but you must remember that the TPMS will not warn of overinflation - only underinflation and many cars come from the factory with extremely overinflated tires.

I'll ask one of the guys down the hall to do some research - or they may know off the top of their head as to what else could cause this - but if it was overinflation then it was more than 3psi.

Arrie

I tried to keep my rear tires at 36 - 37 psi but obviously this way too much. I have new tires now and try to keep them 33 - 34 psi.

MCF

The recommended pressures on the gas door and the driver side door are significantly different. Why is this and which is better?

pdjv

I don't know for sure why the difference, but my 2011 E550 has the optional 18" staggered AMG wheels and the pressures specified on the driver's door are the correct ones for that setup. Maybe the fuel filler door sticker is for the standard tire/wheel setup.