chiromikey

Chalk another one up the MB's effing horrendous nanny systems!

I recently upgraded to aftermarket wheels and decided to up the tire sizes. Nothing crazy, just up one width in the front and two in the rear to 265/35/19 and 305/30/19 respectively. My problems started immediately, reminding me of the "waggle" that many of us experienced in the 55s when trying to run 295s in the rear. The rear end would wander side-to-side under hard acceleration or above freeway speeds. We attempted to rectify what we thought was a hardware problem with beefier toe links and bushings to no avail. This car is even worse. On top of those problems, any sudden acceleration with steering input, such as passing the left lane campers on the freeway, causes the TC to inappropriately intervene and send the car thrusting in random directions. Not pleasant at 80mph!!! Some of that can be mitigated by driving with TC off but just barely.

Last night was the worst of all. I was playing with another guy on an empty stretch at upper end of 1/4mile speeds when I tried to brake hard after the run. The car acted like it was trying to initiate the antilock program and wouldn't allow full stopping power, then caused the car to swerve all over at 100+ mph. This car is outright dangerous as is and anyone looking to run tire sizes other than OEM needs to be warned.

I'm willing to bet that just like the 55s, there will be some cars that suffer this problem and some that don't. I'm considering trying to up the front to a 275 but I'll probably give up the nice 305 in the rear. The other option is to find out if there are any programming options in STAR DAS that allow users to choose tire aspect ratios.

Either way, im so sick of MB programming that prevents me from doing what I want with a car I paid cash for and own.

Savage212

I recently went 255 / 35 / 19 and 295 / 30 / 19 with none of the described issues.

chiromikey

I put my stock rims on the rear just to check and the car drove perfectly.

shardul

iTrader: (1)

In the Developer menu in the ECU there will be a drop down list where you can select a few preset tire sizes that are supplied from the factory that is about it.

chiromikey

Any idea what those sizes are?

RichardCranium

On stock wheels?

chiromikey

It looks like it asks for a dynamic tire rolling circumference for front and rear. Can you enter a value or just select from predetermined sizes?

TTMerc

I always wondered the limits of the 4matic as far as tolerances! Ive run some different setups with luck. Didn't handle the best turning wise on some but TCS never intervened. Glad you and your car are alright! I had an S6 that wouldn't tolerate hardly any difference in front and rear sizes without throwing all kinds of lights.

When I had 20" wheels I ran a 20x9 245/30/20 front 20x10.5 295/25/20 Rear

19" I've had the best luck all around with 19x9.5 all the way around 275/30/19 front 285/30/19 rears.

I'm with you Chiromikey I love the look of a Fat tire on the rear but the 4matic seems to not like it lol


Question: What are you guys using to access the developer menu?

chiromikey

You want to know what's even more ridiculous? I'm not even 4matic!!!!

I think you have to pay extra for a password to access the developer menu but it's been too long since I've played with STAR.

TTMerc

Whhaaaaat? LOL Damn that's cray! What width were the wheels?

chiromikey

front: 265/35/19 on 19x9 et30
rear: 305/30/19 on 19x10.5 et50

iownedu

Did you research and make sure the fronts are the same OD as the rears?

Savage212

No I bought some, CLS63 19" wheels

front: 255/35/19 on 19x9 et:37
rear: 295/30/19 on 19x10 et:47

shardul

iTrader: (1)

You can only select a predetermined size. Not sure what sizes the have but the options are only for the sizes supplied from the factory.

Savage212

Savage212

Very strange as it would appear the OP's setup is closer to equal front and rear than stock?

gaspam

it a mercedes thing lol ... its used to happen on my c63 too and its rwd... for me it happened mostly at higher speeds or on faster turns lik highway on-ramp.... was super annoying and dangerous at times

and i had the rolling diameter of the tires within 1.5% so it wasnt like my rears where huge with some tiny fronts

Savage212

It looks like the OP's setup is well under 1.5% difference? only .4%?

gaspam

yeah mine was too.... 1.5% is just the threshold that most agree to stay under... and it didnt matter that mine was under 1.5% as it did it to me too

chiromikey

I'm hoping I can set the front to back ratios closer to my current set up and keep the car from killing me or someone else! If anyone can look up what available in there I'd appreciate it!

eLs13

Would a 275/30 front and 315/25 rear work?

chiromikey

I don't think 315s would fit but even if they do I'm not even going to guess what the ECU will think...

kponti

Chiro did you get any unrelated CELs that resolved itself?

chiromikey

Nothing related to tires or TC.

kponti

Low boost cel by any chance?