I am getting a tire pressure warning...its says to reactivate...how is this done other than just driving the car? What is the correct pressure for the crapenitals? Checked the tires with hand pressure gauge it reads 40 psi.

There is a reactivation procedure in the owner's manual. You basically have to press the reset button and then drive for a while. 40 psi cold is a little high. I run anbout 34 in all four tires. You can get up to a 4 lounb increase with warm tires.

If you plan to aks the car to turn with any speed be sure to keep the pressures at about 38 psi cold. This will lead to 40-41 warm and at this pressure the car feels far more nimble that at the fairly low factory recomended pressures. Does it ride a bit more harshly? Yes but it is a performance car not a Maybach

38 psi is good.... just re-set the system as per the manuals steps and it should work again. My car has had the TPM system fail 3 times in its 5 month life so I think the system is less than perfect. I still love it however for keeps me from having to look at my tire psi numbers when I go fo an extended canyon drive. I can just watch them go up up and away . That sure beats fingers covered in brake dust!

Thanks....I am goin run 38 cold.

Same problem here...MB quality? Not on the TPM system....otherwise perfect so far.

I thought the front two tires pressure must be lower than the rear, isn't that right?

The E55 is the first car I have seen where the factory did not stagger the tire pressures. They clearly saw the car had a tendency to understeer when pushed for equal pressures tends to help make the front grip more and have the car understeer less.

I never stagger the pressures in any of my cars for it is done only to keep the chassis in an understeer bias. Set both the fronts and the rears to around 38 and go from there.

It is all about what the driver wants as far as ride quality and driving dynamic. A family member runs the tires at or just below factory spec for he likes a squishy ride. To do that in an AMG is nothing short of crazy if you aske me. But he just puttts to work each day at 30 mph so its fine for him.

(WTPMS = Wireless Tire Preasure Monitorin System)
As Mr jkrutch indicated, I've also had problems with the WTPMS, dealer has checked it a couple of times (that is on my E beast). I have now removed the sensors complitely (I now, have always a mulfuction though )

Wiedermann

I have an E500 with the upgraded W rated tires and the pressures are staggered. Check your door for the recommended pressures for your Z tires.

It's my impression that the factory pressures are oriented towards ride quality. There are alternate (higher) pressures suggested for high speed/max load use as well.

There's nothing wrong with higher pressure in the front versus rear tires but this tends to make the car oversteer. Most factory set-ups are biased towards understeer as this is easier for people to control - ask an early 911 driver!

E55 door says non staggered tire pressures...

E500 is a different beast... Got both

SL55 has staggered pressures too... not many MB's are not staggered but the E55 is one of them.

The high load rating for the E55 is staggered but not the normal pressure setting. I just take the normal setting and add 5-7 psi to it and this makes the car feel far better.

Mine came from the dealer with 40 to 41 psi cold.

the TPM is sensative about the correct pressure, I have a 04 SL500 with the TPM and when the outside temp drops here in Colorado the tire pressure drops ( if the pressure in tires hits 24, the TPM gets pissed off and has to be reset ) I had the same thing with my 03 E500. Just have to adjust the pressure to find the happy medium.