MagicJack

There are two different areas where my e550 2wd sedan have the recommended tire pressure listed.

These are cold tire pressures.

1) Gas door flap which indicates
normal load: 30psi front 36psi rear
max load: 33 psi front 42 psi rear

2) Driver B door pillar which indicates 33 psi front 42 psi rear. There is no mention of load.

Is max load the norm? I figure I'd want to keep my tires tuned for 'normal' load.

What should I be keeping the tires at? I just got my car back from its 2nd A service and they pumped all four tires to ~40psi.

K-A

It's insane how the manufacturers can be so foolish as to confuse us with TWO different PSI recommendations. And Dealers always seem to fill up the tires to far too high PSI, making the ride rock hard, not to mention forcing unstable tire wear.

I go with the Gas Cap rating, and keep it at "Normal". I actually usually go to 32-33 F, and 35-37 R when I fill it up (then it naturally decreases over time).

I think the B-Pillar rating seems ridiculously high.

listerone

I noticed the disparity as well.I'm keeping 37psi all around as a compromise.The two stickers recommend anything from 35psi to 37psi....so I'll go with the high figure to save fuel and to allow for forgetfulness abiut regular checks.

ttoE550

Not busting your chops -- this question has been asked many times, with answers all across the board. Your dealer pumps to about 40psi all around. Mine did 32 all around. Dunno about your dealer, but mine sells and services probably about 1/2 the MBs in the DC metro area -- huge volume. Haven't heard about any MBs with tire blowouts, etc. Everybody is confused.

So I guess the correct answer is -- it doesn't matter! Let's just say somewhere between 30 and 40ish with a bit more in the rear and even side-to-side.

hyperion667

I use the gas door numbers too.....although my tpms RARELY displays the correct numbers anyway....they're always different, usually a few pounds.....

ImInPA

Keep in mind the tire pressures listed in EITHER location are referring to COLD tire pressure. Once you start driving, these pressures generally increase a couple psi or more.

K-A

My I/C Display always seems to show about 1-2 PSI less than the actual air pressure device. I assume that means the cars tpms is the inaccurate one.

LaicepsYdobon

I checked my tire preassures yesterday and on my fuel flap it said 32 front 35 back. I have a 2011 E350 4Matic with the sport pack and Pirelli P-Zero Nero tires.

hyperion667

true true....
I have seen it go as high as 40 in the rear; up from 35......

mrnoorde

I know this is an old thread but I came upon it and have some info to add based upon my experience and a confirmation in the 2012 E-Class owner's manual.

The pressures listed on the B Pillar are the cold settings for the max load/max speed. These are the maximum you should set the pressures on your car and should only be used when the car is fully loaded or if you plan to run at sustained high speeds (think Autobahn, so uncommon in America).

The pressures listed on the gas filler flap give you normal cold pressures and cold max load pressures. For regular driving when not running a full load of people/cargo, the normal cold pressures (lower numbers) should be what you run.

Side note, I'm quite sure the reason for this disparity has to do with lawyers and the old Ford Firestone Explorer debacle. It's easier for Mercedes to tell everyone to over inflate their tires so they're covered for all load conditions (with the negatives being possible increased tires wear, rougher ride, and possible tire/wheel damage from bad roads) compared to someone overloading their car at the lower pressures and having a blow-out due to an overheated tire. It's a shame that Mercedes doesn't list each wheel size setup with the normal and max load settings on the B Pillar or gas flap (or both). It's very nice info to have that info for changing wheel size for winter wheels/tires, etc. At least Mercedes should list every wheel size with normal and max load pressure settings in the owner's manual. BMW does this and it's very handy. They even list different pressures for a M+S tire versus Summer tires, as needed.

ghstudio

The information on the B pillar is dictated by NHTSA and other US government agencies.

Mercedes has chosen to help drivers find the tire pressure they should use under normal driving conditions with the auxilliary label on the gas filler door.

mrnoorde

Thanks ghstudio:

That may be the case but the manufacturers are still free to set things up a few different ways. On a BMW B-Pillar, it lists the normal cold pressures for the wheels that came from the factory on that car and also has a yellow sticker next to that with "over 100 mph" pressures for the wheels that came on the car. The main sticker says to see the owner's manual for more pressure information. The owner's manual then lists the pressure for each and every version as well as wheel size, load type, etc.

Personally, I believe this setup is far better and clearer than the Mercedes setup. Just look at this thread.

K-A

I HATE how they list two different Tire Pressure's in different areas. Every time I take the car somewhere where they fill the tires up (or "correct them", as they seem to think), they literally fill them up over 40 PSI, because of that stupid B-Pillar sticker.

mrnoorde

My vote for the correct setup for listing tire pressures:

List both the partial load and full load/high speed cold tire pressures for the wheels/tires that came from the factory clearly on the B-Pillar and the inside of the fuel filler door. Both places should have a clear note to reference the owner's manual for more information.

The owner's manual should then list every available factory wheel/tire size with the corresponding cold pressures for both partial and full load. The owner's manual should also list the cold pressure for the Mercedes recommended winter tires in the various sizes. The owners manual has all the wheel/tire combination listed already but it doesn't reference any recommended tire pressures other than for the spare. Crazy.

As noted, this setup vote is pretty much exactly how BMW does it (other than BMW doesn't have anything listed on the inside of the fuel filler door, it's only on the B-Pillar).

BM2BZ

any of you have the tire pressure screen shown when you turn off the engine?

El Cid

Read the Operator's Manual on tire pressures and read ALL of it. The higher TP on filler lid is for maximum load (5 people + luggage) or driving in excess of 100 MPH.
I use the lower figure and then add two lbs. to that. Periodically I measure tread wear and adjust pressures accordingly if needed. The + 2 lbs. seems to give even wear.
I use a hand pump to add air to my vehicles. That way I can measure when cold and get very precise TP.
BTW, the TPMS indicator in car is fairly reliable, but will often show different pressures per tire. Apparently this is normal and should not be used to determine how much air to add.
My dealer uses the lower figure for my car, probably because I complained about ride. Some may use the higher figure because it supposedly gives better MPG, but doubt it.

ghstudio

Yes, I did. The tire pressure "alarm" is set at the factory (b-pillar) settings. You can,however, easily reset those pressures to whatever you want (e.g. the pressures inside the gas cap) by just resetting it. If I remember correctly, go to the dash display that shows the pressures and there is a reset option right there.

SoCalCLK

I usually roll 34 front 36 rear for 18" wheels

K-A

Is this a Feature where you can have the Screen show you the T/P when you turn the car off, without actually changing the Screen's present Setting (i.e, if you keep it in radio mode)?

ghstudio

I don't think so...it's really a warning message. However, if you don't reset teh pressures, I guess you'll keep seeing it

BM2BZ

i think you are right ghstudio. i don't have time and haven't filled the air for a little while and it sometimes shows 29 front and 33 back but sometimes shows 31 front and 34 or 35 back. funny thing is, like what i said, i didn't even put any gas in and i was driving the same distance. why fluctuate? any idea?

ghstudio

As your tires get warmer, from driving or from the ambient temperature, the pressure rises. That's why they tell you to inflate tires to the recommended pressure when the tires aren't hot.

lamscott

Helpful thread. I've been having the darndest time figuring this out. Especially since my left rear wheel is losing pressure reallly really really slowly, about 2 pounds a week I'm estimating. I've taken that damn wheel in twice already and they can't find any leaks. They told me my TPSM is reading it wrong sometimes but TPSM's usually do that. weird.

Live Oak

IMO, if you buy a $50,000 - 70,000 car, you should buy a really good tire gauge, such as Joes Racing 32307 Tire Pressure Gauge. ($24 on Amazon)

Check and set your tires, when cold, to the pressure you deem correct based on the gas filler door. Use your gauge to do it. IMO, humble as my opinion is, ignore the variety of of old-wives' tales, etc, on radical ideas about what tire pressures REALLY should be. Mercedes, and the tire companies know, and there are no big conspiracies out there. (And re: 9/11, either)

THEN, while still cold, reset the TPMS. TPMS will invariably give you numbers different from your gauge. That's expected, and OK . . . you know what they really are.

From that point on, ignore the pressures TPMS presents in COMAND. Just use it as a warning device. If any tire departs markedly from the setting you will get a warning. If you get a warning, use your gauge, while the tires are cold, to confirm that the pressure is different from that you set using the filler door settings. Again, ignore the numbers from TPMS except to get a feeling as to which direction things are going.

IOW, TPMs is not a precision tire pressure device, but it is a hell of a good variance warning device, and safety device, thus it is a great feature.

As for tire wear, the Central Tools 3S401 Digital Tire Tread Depth Gage is a great idea, although kind of expensive. (What are you going to do with all that money? Leave it to your kids?)

dbtk

I typically run 40 front, 45 rear on by E350 4Matic Sport. I prefer more than less. It does not seem to adversely affect ride nor handling. Plus I get better fuel economy and slightly more precise steering feel.