I have an S550 4matic. I noticed today that the front tire size is 255/35/20 and the rear tire size is 275/40/20. I thought that on AWD cars, the tires must be the same rotational diameter, and on mine, they're not. Is it different with benz?

I called Mercedes, and they're like, yeah that's normal. I know on my Lexus, they had to be the same rotational diameter. On my VR-4 they got to be the same rotational diameter.

OEM - they are supposed to be the same size...technically, they should be 255/35/20 on all 4 corners. People run staggered sizes as long as they are within 3% and have no issues.

Well i'm no so much concerned about them being staggered. I'm concerned that they're aren't the same thickness, therefore they don't have the same rotational diameter. The width isn't an issue i'm aware, it's the sidewall i'm worried about.

The only thing you can do is put 255/35/20 on the rear. You can't run a 275 on the front.

Again, i'm not concerned about the width. Staggered is fine i'm aware of that. It's the rotational diameter i'm concerned about. 35's in the front and 40's in the rear. Not the width, but the diameter, since it's AWD.

So, what is it that you are asking or looking for? Did you use the tire size calculator to see the rotational diameter???

What? No, lol. the rear are 275/40/20 and the front are 255/35/20. Not only can i tell from looking, but the size says it all.

What i'm asking is, since on Porsche, Mitsubishi, Audi, and Lexus, the same rotational diameter is required on AWD cars, is it the same on Mercedes?

Did someone **** up on my car before i got and put the wrong sized tires, or does mercedes drive train allow for different sizes.

Read my 1st reply...that answers your question.

Your first reply is referring to the fact that they are staggered. Mine are not only staggered, they are staggered with different diameters also.

So basically i'm fine with a different diameter tire on front and back?

Sorry, just really want to make sure, 'cause if i did that on my VR-4 i'd have tranny issues.

Preciate you taking the time and responding.

K, staggered refers to the width of the tire/rim. Staggered means different width tires. My questions has nothing to do with the width of the tires whatsoever. I'm not asking about staggered at all, nowhere in my questions is there a questions about staggered, or about width. I'm completely comfortable with the width of my tires, happy with the fact they're staggered and have absolutely no concern with that.

Let me rephrase the questions. If i was running NON STAGGERED tires, 255/35/20 in the front, and 255/40/20 in the rear, would the difference in circumference matter on a benz?

Thanks anyway.

such as

http://tire-size-conversion.com/tire-size-calculator/

it shows it is a 5.7% difference which is way too much

these are not stock rims that came from factory and the previous owner was unaware of this

read the rest of what i said...it doesnt matter if they are staggered or not, it's about the tire size. All you need to do is look at a tire size calculator...

"as long as they are within 3% and have no issues."

should prob be 275-35-20, go on tire rack and see the stock size.

Well the tires are new. So i'm going to have to change either the front, or the back. I'd prefer having a quieter ride. I'm not ripping corners with this thing anyway so i'm leaning for the 40's all around. So, should i go with 35's all around, or 40's? what do ya'll think?

while it's not an 07, I have 265's on all four corners

I"m not very concerned with the width. What size sidewall are you running?

35

Do you realize the height (sidewall) of the tire depends on the width right?

275 = width (in millimeters)
35 = 35% of the section width of your tire is the sidewall height measurement.

So a 275/35 can have a taller sidewall than a 195/40.

So you SHOULD be concerned with the width as the other number is based on the width.

If your wheels are staggered, when mounting all 4 same size tires will cause rear tires to have stretched look.

Like i said in every single reply above:

What i meant was that i'm aware having a staggered setup isn't harmful to AWD cars, so i'm not concerned that they have different widths. I was concerned that they have different rotational diameter.

So no, i'm not concerned at all that the back tires are wider than the front.

Plain and simple for our 4matic setup is you have to run all 4 tires the same size!

Rears are the wrong size should be a 275-35-20.

You ****heads are dumb. The S550 4matic comes from the factory staggered.