Thread: Upsizing wheels
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Old 10-05-2010, 10:31 AM
shadowless shadowless is offline
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Quote:
Originally Posted by elb1999 View Post
2007 X3......go from 17" wheels with standard 235/55/17 to an 18" wheel and was thinking 245/45/18 tire. I know the standard 18' tire size on the X3 is 235/50/18....should I stick with standard size or go wider and lower? Any experience?
there is no real harm in going with a tire size for 18" wheels that is different from bmw's standard size. however, in this case, 235/50/18 is closer to the total radius of the 235/55/17 than 245/45/18. this means that your speedometer will read closer to the way it did before.

Quote:
Originally Posted by AzNMpower32 View Post
You're better off going to what BMW uses for the 18", that's what I did when I bought a set of 18" summer wheels/tires, and I still use the 17" for winter tires.

There are more tire choices in the P235/50 R18 size and proportionally that size looks proper as well.
+1

OP, unlike the recs of others who have replied, i do not recommend staggered setup f/r on an awd car especially if the radius difference between front and rear wheels is significant. the reasoning is the same for why it is strongly recommended that you replace all 4 tires (or have replacement tire shaved) when you get a flat if the tread depth is signifcantly less than the brand new tire depth.
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