magicbyswh

I am a new 2009 E350 owner I have 2 questions can someone post how to reset the Service indicator? Also I have the sport sedan with the AMG 18 inch rims but different tire sizes on the front and back. From the manual the fronts tires are 8.5 and rear 9.0 is this correct if they are both 18 inch rims? I Can you rotate the tires on this car?
Thanks for your help
Steve

amdeutsch

For the service reminder there is a sticky at the top of the forum.

Why would you want to put wider wheels/tires in the front and narrower ones in the back?

pinebaron

You cannot rotate tires front to back only left to right and vice versa for non-directional tires. Service reset instructions attached.

amdeutsch

You pdf has the wrong info on page 6. See this thread from konigstiger: Link

Barry45RPM

Very simply put, "18 inch" refers to the rim or wheel size (height without tires mounted on them) , or the inner hole diameter of your tires. 8.5 and 9 refers to the width.

There are other tire dimension factors too, such as the profile... low profile/high profile, which refers to the distance from the edge of the rim to the outer edge of the tire, commonly thought of as the "tire wall"... the part with all the writing on it.

Your car has low profile tires, which means you should try to avoid bad pavement/pot holes, as there is not alot of tire there to absorb the bump, and wheel damage can occur.

Since these are not "Race Cars" designed for ultra high performance in day to day driving, the staggered wheel set up (different sizes front to rear) is more "sizzle" than steak, although they do give you a bigger foorprint in the rear. All 4 the same size makes more sense Dollar wise to most drivers. Such is the price of "Sportiness".

220S

Having a wider patch where the drive wheels are will give you better traction. Although the traction really comes from the softer compound that wider tires employ and not so much the contact patch (normal road surfaces are uneven.)

Friction doesn't depend on surface area, but the softer wider tire does relate to a bigger coefficient of friction. Wider tires also have stronger sidewalls which is an added benefit for handling with less body roll.

But, as Barry says, this is in theory and not applicable for most daily drivers with a weaker right foot.

FKD

The purpose of a staggered setup (wider tires at the rear) is to reduces oversteer. It is for high power RWD cars that are prone to torque induced oversteer (rearend stepping out while cornering fast). The extra width in the rear tires makes the rearend harder to slide out.

220S

It helps reduce oversteer on cars with oversteer (like my C2S; 235/295) However, these cars tend to have an understeer bias as it is, and so in reality a staggered set up doesn't really do a lot in the end. Esp in real world driving with the vehicle in question, which is not a 'high powered' car. Although yes, the theory is correct: faster front tire turn-in and a wider sticky rear to help with any oversteer.

Which is what I was talking about re: traction.

But for an E350, it's really not necessary for the majority of drivers. And it means no rotation with directional tires. On a E63 or M5, it makes more sense.