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      12-23-2012, 10:23 PM   #54
Major General

Drives: 340i M-sport AT
Join Date: Mar 2006
Location: Chicago

iTrader: (1)

Originally Posted by Sweeper View Post

Ok I have bad news for everyone. I've been to my dealer. The answer is :

IF you have a Xdrive M-sport(M-paket) in 18 (style 400M) with staggered(8x18 and 8.5x18) setup 225/45/18 and 255/40/18 summer setup. The ONLY way to put winter tyres and don't have DSC problems (and possibly not ruin bmw warranty on differencials) :

1) To put 225/45/18 and 255/40/18 winter tyres WITH RUNFLATS. I installed non runflats(pirelli sottozeros) in the same setup and DSC is failing. This is due to the fact winter tyres has softer structure and DSC will fail on non runflats.

2) To put squire setup (all tyres are the same) , but you will have to buy 2 additional front wheels to put on the rear 8x18 (as rears are 8.5x18).

So welcome to the world of bmw sales. I actually don't know is it worth to hunt for runflats or buy 2 more wheels , as the tyres size is quite rare and I can't fit other wheels (less than 18") because I have M performance brakes
Very strange. Xdrive must be overly sensitive.

With AWD you have to make sure that the front and rear tires all have the same diameter.
Did you also make sure you were running the proper tire pressures front and rear?

If all of that is correct, I think BMW needs to answer as to why non RFT's, with the same diameter, and proper psi are causing the problem.
I'd like to read their explanation as to why RFT versions of the same tires will work.

Last edited by RPM90; 12-23-2012 at 10:33 PM.