^ This Nokian article refers to the rating standard to earn the snowflake within the mountain.
"In order to meet this standard, tires must be tested using an American Society for Testing and Materials (ASTM) testing procedure described in “RMA Definition for Passenger and Light Truck Tires for use in Severe Snow Conditions”. Tires designed for use in severe snow conditions are recognized by manufacturers to attain a traction index equal to or greater than 110 compared to the ASTM E-1136 Standard Reference Test Tire when using the ASTM F-1805 snow traction test with equivalent percentage loads."
http://www.snowtyres.com.au/severe-service-emblem
Seems like a lot of Nokian users here. Thus, I will ask did anyone note any problems ( transfer case, driveline shunt issues, balanced) associated with these non BMW approved tires? Also, kindly state whether your experience is with RF or Non-RFT. I had 3 sets of the WR2 ( year round use) on non-BMW's, excellent for my location not too much snow. Looking to buy another set. I concur for lots of snow, going skiing, lots of winter driving then R2, is best option over WRA2/3.