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[petesamprs]

What's the rule for when to switch over to winter tires. 330i SP is arriving in early November...it'll definitely be cold but might be a few more weeks before real snow. How soon do you guys switch over? This is for northeast US

[Nikki]

I used to put mine on mid October, or at least by November.
A few years ago I went to put them on in October, and on the way to the dealer it started snowing!

[iDrive-E90]

There is wide variation form year to year. Here are some statistics for Boston (sorry I can't get the columns to line up for some wierd reason):

Date of First Snow
Earliest Mean Latest
Trace Jul 10 1955 Nov 4 Dec 16 1973
1/2" Nov 4 1945 Dec 5 Jan 7 1958
1" Nov 10 1976 Dec 12 Jan 29 1928
2" Nov 11 1987 Dec 23 Feb 16 1980
3" Nov 11 1987 Jan 1 Mar 19 1992
4"* Nov 12 1987 Jan 10 Mar 19 1992
5"* Nov 12 1987 Jan 18 Mar 19 1992
6"* Dec 2 1929 Jan 23 Mar 29 1970
*did not occur in some years

Here is the source which is a little easier to read

http://www.erh.noaa.gov/box/climate/snowbos.html

[Bimmerista]

In helping you make a decision, please note that with the sports package we get high performance summer tires. When the temperature drops below 10 degrees Celcius (someone help me please witht the Farenheit conversion- 50 degrees ?) the compound becomes hard as a rock and as a result the slightest sign of humidity can make the back of car become the front really quickly and without much warning.

As a result, I go by average temperature, not likelyhood of first snow. Up here in Montreal Canada the third week of October is a good time to put on winters.

[petesamprs]

Yes I think 10 celsius is 50 fahrenheit. Ok, that's helpful...basically I should put them on right when I get the car. I guess she'll be broken in on winter tires.