i believe sidewall sizes for 19s are 45/40.
any owners here have increased their 20s to these from the standard 40/35?
if so, does this shoot off any sensors and/or dramatically misread the car speed?

i'd love to get a bit taller sidewalls for greater "cushion" on my oem 20s.

 

also... what detrimental impacts, if any, if i went same 45 sidewall height for both f/r?
the ps4 AS are limited sidewall sizes for 20" 285 rear

 

The rear steering if you have it may make a difference to keep in mind. I have 10 degree and the clearance appears limited (to me) at the full 10...

 

If you keep your 20" and go with a higher profile, that's about a 1 inch increase in overall diameter, so hopefully you'll be able to feel a positive difference.

The ABC/ESP and 4Matic sensors are not triggered by the overall diameter, but rather by the difference between front vs rear wheels. You just need to make sure you have a difference of no more than 5% for the rotational speed between front and rear, and if so, so u should be fine as far as sensor. There are some calculators online to double check the rear vs front difference in diameter (again, should be less than 5% difference between front and rear no matter what size you choose). You are probably fine since you are increasing both rear and front by the same value anyway, so your original front to rear difference should be maintained.

By the way, the S63 E Performance (AMG) actually uses 255/45R20 and 285/40R20 as a factory size, so you might be able to keep your current 20" as planned and just go with 40/45 with that wheel. Again, the factor that matters the most for 4Matic and sensors is the difference in speed or rolling circumference between rear and front, not just the overall diameter. Check some calculators online to confirm the rolling circumference between your current size and the other one you wanna go with. Remember that the rolling circumference is a function of width, radius and the tire profile not just the profile. I did something very similar in my 7 series by going with slightly wider tires than factory, and the ride comfort is better now although the reason I did is to get All-Season NRF and the ride quality was just a 2nd factor I didn't care about.

One thing to keep in mind for your case, when you increase the profile, even though the sensors and 4Matic system is fine, your measured speed may change if you increase the total diameter of the tire and keep the 20s. Larger overall diameter means faster actual speed when your speedometer is reading lower values. This is a good calculator for that: https://tiresize.com/speedometer-calibration/

 

so based on above, going 45/45 would be ok cuz the difference is 0?

 

No, that's not what am saying because I didn't do that math. I just said that the difference needs to be (less than 5%) between front and rear. Even standard size is not 0% but should be below 5% by the way. Check the sizes that you are switching to and make sure the rolling circumference is less than 5%

Use this calculator below, and use the 2nd table on the home page, add both sizes that you want to compare, and then then look for (Tire Circumference) difference under the results. Tire 1 should be your front and Tire 2 should be the rear. Do it once for the standard size and you will find that the Tire Circumference is below 5% as it should. Then do it again wherein Tire 1 and Tire 2 are your NEW tire dimensions and make sure that the Tire Circumference difference between your NEW front and rear remain also below 5%. You can also use this calculator to compare new vs old dimensions but in that case Tire 1 and 2 will be your old front vs new front as an example.
https://www.calculator.net/tire-size-calculator.html

If you can't figure it out or use the calculators, just post your full tire sizes (current) as well as the new one with all dimensions, and I can run the calculator for you when I sign in again in the evening.

 

ah gotcha.
then going 35-->45 in rear wouldn't work by that math... the difference is greater than 8%.

sucks cuz ps4 AS in 285 does not come in 40 profile.
if i go 295 i can get to 40... would that bulge out too much on oem 20s? anyone have this 295/40 in the stock rear?

 

I have another idea for you. How about you just go with wider tires and keep the profile the same? Keep the profile the same (35) and go from 285 to 295 (and same plan for front, just 10mm wider with same profile). I literally did this same exact thing on my i7. Remember, the profile number is just a (percentage) of the tire width. So, wider tire = more comfort, and it also means higher profile. 35 on a 295 tire is higher than 35 on a 285, cause the 35 is 35% of the width.

my OEM i7 21" stagger were: Front 255/40R21 and Rear: 285/35R21
I replaced them with NRF all season, slightly wider to Front: 265/40R21 and Rear: 295/35R21

The net change I did by doing that is that my overall diameter is 1% larger now (I got 10mm in width as well as 4mm extra cushion). The net increase in diameter in the front was 1% and the same exact is 1% in the rear, which means my new rolling differential compared to OEM is net 0% (aka, my new front-to-rear rolling diameter relationship essentially the same) but now I have wider and slightly larger profile for much better comfort, and much better tires, cheaper tires and more accessible size too! Another benefit is that the stance of my car looks better now with 295 in the rear. On turns, although I don't feel much difference as I have active/mechanical anti-roll bars, the car should be more sharp/flat on turns at least by math.

So for you, you can do the same by going with 255/40R20 --> 265/40R20 on the front, and 285/35R20 --> 295/35R20 for the rear. This approach is less risky, but will get you the benefits you are looking for. I think the visuals will look better too. Increasing the profile randomly will make the tire ugly. But wider tire with (less) proportional positive increase in profile will not change the aesthetics. Yet you would get the outcomes you are looking for. More comfort combined with better look honestly. Your MPG mathematically would be 1-2% lower but who cares when it's more comfy then and better looking. You speed difference also would be just 1% as opposed to 3-4% for your originakl plan, and your rolling diameter difference front to rear would be similar (just <1% difference from OEM) and within the allowable 5%

 

was thinking similarly, per my last post. glad to hear someone's had positive results doing same.
MB made terrible choice with the stock profile size - ur i7 on stock 21s are 40/35 whilst the MB is 35/30. no wonder the 21s on the w223 are getting so many complaints.

will look into changing my 20s from 255/40 285/35 to 265/40 295/35... thanks for suggestion!

 

One thing I noticed after going with the S63 tires size on aftermarket 21” wheels is that the speedometer readings isn’t affected.
I expected a slightly lower reading vs. actual speed(GPS) but to my surprise, the speedometer showed 1-2mph above the gps speed- same as the OEM wheels/tires I had.
I guess the speed sensors are not simply reading the rotational speed of the wheels.

 

Here’s what I run: F: 265/40 R21 105Y and R: 295/35 R21 107Y

I did adjust my ghost links about 10cm higher (when the car is in sport + mode) due to the lowering of my S580 at high speeds no speedometer problem at all

 

u increased both width and sidewall on the std 21" tire specs😮 nice!
what tire brand/model r u running?
I'll probably stick with 20" due to the common blowouts reported on 21s (hell, even on my 20s with stick hankook i had a blowout!).
although i wonder if ur double increase on tire size entirely removes this issue on the 21s..??

also would u mind posting 3 shots of urs on the ghost links... raised, comfort and sport.

 

btw... as i need to get all-season tires (located in the northeast), noticing that the right combo of tires sizes outside of stock spec is not widely available.
any owners having have had good experiences with increasing size on their 20s with AS tires, world love to hear what brand/model.

 

have you tried calling tirerack? they can do the calcutaions for you.

 

rather looking for actual owner experiences.

speaking of...
any 21" owners increase their profiles same as s63 spec (255/40 and 285/35)...still prone to blowouts and bending?

 

Replied to your PM.
I think the S63 OEM tires (PS4S) provides better sidewall protection compared to the other same profile options.
MB must have spec'd it better than the standard S580 considering the 5700+ lbs. weight of the S63E

 

unfortunately need to get AS tires for the northeast weather.

 

Sure; they will be labeled according to the heights in the photos.

 

woa...huge!😮

 

Yeah, the 21" wheels with 40/35 profiles fill the wheel house nicely.