don`t know nuthin aboot no transfer case
just thinking those boobs could generate some power whilst they wave about .

T-Case failed on our 2004. Dealer said non-OE spec tires on factory staggered optional wheels was the culprit. I was running the correct size tires, but circumference varies between tire manufacturers and that was enough to do it in. I suppose, but reamain skeptical.

You're not the first one, it's happened in Germany as well.

The best things to do:
1. Always reset the Flat Tire Monitor when correcting tire pressures and changing tires and/or wheels.
2. Change out the transfer case fluid at Inspection II. The cost of a fluid change is, needless to say, much cheaper than replacing the transfer case later on.

I've followed the above two steps, and despite various tire changes and a separate set of winter and summer wheels/tires, the T-case is A-okay on my 2004 with 98k miles. Knock on wood.

I had to have my oil changed .

does anybody know about bentley pub for bmw x3. I searched but it seems it does not exist.. :dunno: WTF

It seems many of the faulty transfer case are caused by the small electric actuator. BTW many x3 owner in Italy have had it fixed. Has anybody had the opportunity to open one of these electric actuator and explain what is inside?

WHAT?

Which part isn't clear? Anything beyond approximately 3" [EDIT - 3%] difference in rolling diameter front/rear stresses the transfer case and risks damage. With a pre-2004 X5 solid transfer case that shows up in problems with the splines. With an x-drive transfer case in either an X3 or X5 that shows up in wear to the clutch packs. Different manufacturers of tires have variations in actual rolling diameter, which is why many tire stores will want to replace your tires four at a time, not two at a time, so you don't come back and blame them if you have problems with a transfer case later.

I run different brands front to rear on both Xs right now, but when I pressure up I make sure the center height of the wheels is the same on the front and the back wheels even if that means deviating from the ideal inflation pressure by a couple of psi.

The worst difference I have seen though is less than 1/4" and that does not really translate in to >3" circumference. To get >3" difference you would need over a 1/2" off on the rolling radius....... Generally tires don't vary that much between brands but it is worth checking when you mount new tires that they all have the same radius.

Sorry, it was a typo. BMW's limit is 3%, not 3". You can't see that small a difference.