Replacing just the rear tires ok?

[JCL]

Originally Posted by Sundayjumper

How ? The planetary gear in the transfer box acts exactly like an open differential, there's no locking mechanism that will allow transmission wind up.

I don't think it is wind-up, as with a fixed part time 4wd setup, but I do think that a constant speed difference between front and rear contributes to transfer case wear. The same can be seen with a differential in an axle that is designed to allow for differences left and right, but which can wear out due to constant speed differences. Spinning one wheel can do that quite quickly.

BMW techs on the board have commented that they have seen damage to transfer cases from tire size differentials. I trust those techs. I do know the front output shaft is somewhat weak anyway, due to the limited spline engagement, but will defer to the expertise of a dealer technician.

I have personally only seen DSC errors due to the difference in rotational speeds.