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      10-30-2012, 12:34 AM   #1
edx1
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Drives: X1 xDrive35i
Join Date: Oct 2012
Location: Wasatch front

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323 wheels and different front/rear widths question

I was digging through some option codes for the xdrive35 and noticed that the 323 wheel option actually had 18x8.0 (225/45 R18) front and 18x9.0 (255/40 R18) rear. This fact isn't mentioned (that I could see) on the bmw website or configuation tool.

First thing is don't see why they would do this on an xdrive. On a RWD only car I could see larger rear wheels for drive grip but what does wider rear wheels do to help an AWD?

I've also been reading threads where they say (for xi models) don't do this because it causes problems with the dsc and early failures with the awd components. I would think it would cause the same problems on an xdrive as well.

Could someone enlighten me on what's going on?

And are the actual wheels different dimensions? One is a /40 and the other is a /45 which also confuses me on why they'd do that.

Last, I live where it snows, often I have to drive a mile in 4"-8" of snow a couple times a winter and there are practically no options for winter runflats (I think there was 1 and it had only 3 very bad reviews on tire rack). I guess I could get different wheels for winter that had more common width (and same front/rear maybe?) sizes but I need to know if the fronts and rear actually have the same outside tire diameter (/40 vs /45 on r18) and if their wheels are the same dimensions, minus the widths.

Thanks.
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