[Alex_Barnes]

Hello,

My xDrive has the following factory setup:

Front: 245/35/R20
Rear: 275/30/R20

Currently all my tires are sitting at around 7.5/32" tread depth. I've got a puncture on the rear and need to replace the tire, the new tire is 9.5/32".
I've been reading up to find out xDrive vehicles are extremely sensitive to variations in overall tire circumference and all tires should stay within 1% of each other.

Will this variation cause issues with the transfer case? Some threads mention as long as the difference in tread stays within 2/32" it should be fine.

The brand new factory setup comes with an almost 1% variation, leaving literally no room for uneven tread wear/driving style/cornering etc..


Based on the calculations above, the rear's are the "smaller" tires so a new tire with more tread on the rear would be better, right?
But then what about the other side of the axle?

Perhaps BMW approved tires have slightly different tire treads when new help offset some of the difference due to the staggered setup, its just 1/32" though, thats not good enough to correct the 1% factory variation - who knows



Also any suggestions for actually measuring the circumference of the wheel? Jack that side up and wrap a measuring tape around it perhaps, any more convenient/accurate suggestion?

Thanks for any help in advance.