Staggered Tire setup issue - PeachParts Mercedes-Benz Forum

davis449 · #1 11-29-2006, 09:01 AM

First of all, yes I did a search and found some of useful info. I am currently running 235/45/17 in front and 255/40/17 in the rear on my 99 C 280 Sport with AMG stlye III's staggered (switched from the stock 16's). My cruise will not set and hold above 74 MPH (and on when terrain changes it doesn't hold that very long), which in reality (checked with GPS) is about 77 MPH. This is annoying as the speed limit is 80 MPH on I-10 in West Texas where I travel a lot. I did some reading in a previous thread from about 2 years ago and saw that overall diameter is probably the culprit. Right now the difference in overall diameter between the tires I have is .30. It doesn't seem like that much Is that enough to make cruise stop working? I've noticed that the difference between a 225/45/17 and the 255/40/17 is .06, which seems MUCH closer. Should I go ahead and purchase 2 new 225/45/17's for the front and try to get my cruise working again?

This whole thing puzzles me because the difference between a 225/45/17 and a 245/40/17 (stock C 36/C 43 setup) is .25 which isn't that far off from my current setup. I guess the real question I'm asking is: Is it the new rim size I threw on or the difference in tires size that's screwing with my cruise and ASR (to a much lesser degree)?

ROGER E. · #2 12-07-2006, 12:20 AM

It might be useful to determine the revs-per-mile difference, front to rear, and find out what the maximum tolerance is. If this number was too high, I can see that the ABS would turn off but don't get the cruise control connection. The stock tire sizes for those wheels (assuming they are 7.5 & 8.5 wide like the C36 wheels on my C320) is 225/45-17 front and 245/40-17 rear.

ROGER E. · #3 12-07-2006, 12:35 AM

Using your tire sizes, I calculate that there is a 22 revs-per-mile difference, front to rear or about 2.73 % difference. Doesn't seem like much.

sye73 · #4 12-07-2006, 03:42 AM

I'm not sure if I have understood this fully, but something that stands out to me here is the rear tyre sizes. If you're using 255/45/17 in the rear and the original equipment for c36/c43 is 245/40/17, then this represents a big difference in overall diameter ( around 25mm ). Although I am not 100% sure on this, I thought that Mercedes had wheel speed sensors - if this is the case, then I would expect the system to pick up this mis-match and possibly cause the issues you're having.

What width are your rear wheels ? A 255/45 seems very 'big'.....

It would also be better to get the 225/45/17's for the front to loose the 9mm increase in overall diameter that you have.

Luke@tirerack · #5 12-07-2006, 01:31 PM

you cruise will not set because the rear tires are too tall and are rotating slower than the front ... you need 255/40-17 in the rear

davis449 · #6 12-12-2006, 11:40 AM

Ok, sorry I haven't been able to check this thread in a while. I am running 255/40/17's (I corrected my 1st post) on an 8.5 width AMG Style III rim in the rear and the same AMG Style III's in 7.5 width on the front with 235/45/17's. I did some research and I think if I switch to 225/45/17 in the front, it should allow the cruise to work again. If you put the stock-size staggered setup from a C 36/C 43 on the tire calculator you will see that there is more of a difference between the 225/45/17 vs the 245/40/17 than the 225/45/17 vs the 255/40/17. So therefore the 225/45/17 would be a better match for my rear tires than the 235/40/17's I have on the front now. This also means that the 255/40/17 is a better match for the 225/45/17 fronts that are on the C 36/C 43 stock.

dkveuro · #7 12-14-2006, 04:48 PM

Quote:

Originally Posted by davis449

First of all, yes I did a search and found some of useful info. I am currently running 235/45/17 in front and 255/40/17 in the rear on my 99 C 280 Sport with AMG stlye III's staggered (switched from the stock 16's). My cruise will not set and hold above 74 MPH (and on when terrain changes it doesn't hold that very long),

This whole thing puzzles me because the difference between a 225/45/17 and a 245/40/17 (stock C 36/C 43 setup) is .25 which isn't that far off from my current setup. I guess the real question I'm asking is: Is it the new rim size I threw on or the difference in tires size that's screwing with my cruise and ASR (to a much lesser degree)?

Any rpm difference in the rolling diameter of the tyres..side to side or front to rear will set the EBR / ETS / cruise control etc etc, or any brake/steering stabilisation systems into 'deactivated' and will illuminate the brake/traction lamp on the instrument panel.

There is very little error margin in the systems and they shut down if there is any deviation from factory programmed tolerance and will not reset untill ignition key is recycled. Dust and dirt on the tone rings will also activate a OBD code and switch to default, safe mode.

.

.

ROGER E. · #8 12-14-2006, 11:00 PM

<<There is very little error margin in the systems and they shut down if there is any deviation from factory programmed tolerance and will not reset untill ignition key is recycled.

There has to be some wiggle room since differing tire wear rates must be considered. In my case, my C320 eats rear tires at about 2.5 times the front tire wear rate and I've never had a CC problem related to that. I presently have my final set of Bridgestone SO-3s on AMG 17s, 7.5" & 8.5".

RE/SEA

Bob C. · #9 04-30-2007, 12:28 AM

Gentlemen, I am considering a used 211 4matic that has a staggered set up. Stock is 245/45-17 on all fours. Revs for stock (michelin tire) is 809, with a 25.7" diameter.

This vehicle has plus-one, 245/40-18s up front (with identical revs and identical diameter to stock); however, the rears are 265/35-18s (instead of the tirerack suggested alternative of 275/35-18). The rears have 822 revs at 25.3" diameter.

Will the different revolutions/diameter damage the 4matic system or transmission? Or is the difference (.4") small enough to allow everything to work properly? Thank you all for your insight!

Regards,
Bob

t walgamuth · #10 04-30-2007, 02:07 AM

that seems crazy with awd.

tom w

Bob C. · #11 04-30-2007, 03:36 PM

I know that most run the w211 4matics with identical wheels front and back. However, given that the rotations and wheel diameters are similar, and that no codes were thrown, would a staggered set up pose a problem for the 4matic system or transmission? Is the .4" variance on the rears insignificant? Thank you!

Regards,
Bob