Quote:
Originally Posted by ukr
Going with aftermarket wheels and different tire sizes is tricky on an all wheel drive car. You have to maintain OEM tire diameter ratio between front and back or your transfer case will be toast quickly.
|
Below is part of the email I sent to my buddy at BMW Bellevue before I made the change
STOCK
-------
275/35 = 86.6
285/35 = 87.5
... front:rear circumference delta = 0.9" (rear is larger)
ME
---
285/35 = 87.5
295/35 = 88.3
... front:rear circumference delta = 0.8" (rear is larger)
... - 0.1" relative to stock
He said BMW won't confirm whether my -0.1" circumference delta is supported or not but he felt it was within tolerance since it's actually closer to 1:1.
@OP, here are your numbers. I don't understand the tolerances at play here--I'll leave that to the experts--but the difference is substantial enough to give me pause. I'm not sure if the reversal as to the larger circumference is significant.
OP
---
285/35 = 87.5
305/30 = 85.4
... front:rear circumference delta = 2.1" (front is larger)
... + 1.2" relative to stock