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-   -   40 vs. 45 series winter tires (http://www.bimmerfest.com/forums/showthread.php?t=650229)

cbooty9001 10-06-2012 10:25 AM

40 vs. 45 series winter tires
 
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?

Orient330iNYC 10-06-2012 10:41 AM

they are an inch smaller. more susceptible to pothole damage. in terms of sidewall height, equivalent to running 19" rims with the correct tires. your car will also rack up mileage faster

tturedraider 10-06-2012 11:13 AM

It is a ratio of the width. 40% of 225 mm v 45% of 225 mm. Are you just having the tires swapped on the original wheels? Better for winter tires would be something like a 215 on a 17" wheel or even a 215 on the 18" wheel. Narrower gets through the snow better. Have you checked winter setups on www.TireRack.com?

Orient330iNYC 10-06-2012 11:14 AM

Quote:

Originally Posted by tturedraider (Post 7117557)
It is a ratio of the width. 40% of 225 mm v 45% of 225 mm. Are you just having the tires swapped on the original wheels? Better for winter tires would be something like a 215 on a 17" wheel or even a 215 on the 18" wheel. Narrower gets through the snow better.

+1

17" snows are cheaper as well.
the cost of mounting and balancing twice a year (if you plan on just swapping tires) pays for new 17" rims in about 2.5 years

Yobyot 10-06-2012 07:56 PM

Quote:

Originally Posted by cbooty9001 (Post 7117489)
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.

Orient330iNYC 10-06-2012 08:20 PM

1 Attachment(s)
Quote:

Originally Posted by Yobyot (Post 7118258)

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.

what have you been configuring on tire rack?
http://www.bimmerfest.com/forums/att...1&d=1349580002

Elk 10-06-2012 08:32 PM

Quote:

Originally Posted by Orient330iNYC (Post 7118302)
what have you been configuring on tire rack?

I am wondering as well. I bought a set of four alloy wheels, Blizzak WS70s, TPMS, mounted and balanced for ~ $1,400.

Saintor 10-07-2012 05:35 AM

Quote:

Originally Posted by Yobyot (Post 7118258)
This would be a BIG mistake.

I agree. IMO the ride quality is very different. I had two sets of summer 225/40/18 and was ready to "downgrade" to 17", fed up with the ride quality (my winter 17" were riding just fine). I decided to try 225/45/18 and now my ride quality is just fine. In my case, I know that I have a speed error of 3.4% but that's not a big deal to me.


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