215/45-R17 OEM's...Which size winter wheel?

Hi...Newbie here...Please excuse me if my question is as obvious as... (been reading in many threads, but answer to my question eludes me)

I am a new Mazda6 owner here in Europe(Sweden), and just preparing for our customary bad winter! On my new Mazda 6, I have standard 215/45-R17 dimension wheels. I need something for the winter's ice and snow, so after reading thru this forum, I have decided to go for 16"alloys. But its the rest which is confusing me right now...Do I go for 205/60-R16, as recommended by many people on here? I have looked at the wheel calculator (http://www.wheelsmaster.com/rt_specs.jsp) and the difference in diameter is 26mm greater. Is this ok for the Mazda6? I dont wish the speedo to be out by much, although if its just 4km/hr out whilst reaching a speed of 100km/hr, it doesnt matter.
On all my documentation, I have read that I should go for exactly the same size wheel, but reading thru this forum, it isnt necessarily the case. Should I stick with the original size?
Also in general when purchasing the wheels, do I need to specify the bolt pcd of 5x114.3, or is this Standard when I quote the wheel dimensions eg.205/60-R16?

Thank you in advance...

[Tire Guy]

Welcome to the boards! There are some differences between the North American-spec 6 and the European/Asian spec 6. Notably, different tire sizes. For Europe, you'll need to use 205/55R16. The 205/60R16 is for North America. Here are some additional specs you'll need to know about the Mazda6's wheels and tires.

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