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Old 10-06-2012, 07:56 PM
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Yobyot Yobyot is offline
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Location: Boston
Join Date: May 2005
Posts: 352
Mein Auto: F30
Originally Posted by cbooty9001 View Post
Just got a new 2012 328i and need to get some winter tires. I noticed 225-40 R18's are quite a bit cheaper than 225-45 R18's (I assume it's a more standard size) and was thinking about installing the 40's instead of the 45's.

I know this will throw of the speedo a bit but other than that, wondering if anyone has any experience with this.

Worth it to save a few $ or not?
This would be a BIG mistake. 225/40R18s give you a standing height of 25.08661417. If you have 225/45R18s on your car now, that is a standing height of 25.97244094. This is a -3.53% difference -- significant.

The correct -- and less expensive -- option for winter tires for the F30 is 225/50R17, whose standing height is 25.85826772. That's only -.44% difference from the factory tires.

If you searched for how to find the correct plus and minus sizing for cars on the net, you'd find many calculators to help.

The BMW p/n for a set of wheels and winter tires in size 225/50R17 is 36-11-2-298-928. I've seen this as low as $1895 for four, mounted and balanced. Nothing Tire Rack offered me came close.
MY12 335i ZSL with a deep dive into the options list
Produced: 2012-06-22
ED: 2012-07-19; Arrived in Jersey City: 2012-08-23
Redelivered: 2012-09-12
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