Can anybody explain what is the difference between Blizzaks winter tires WS-50 and LM-22?

The only difference I see is speed rating, but I'm not going to go much over 100 in winter anyway.

Yesterday I was in tire shop and saw Bridgestone's stand with tires information. WS-50 was rated there overall higher than LM-22. Also, I've read some customers reviews on 1010tires.com, who put WS-50 on sports cars and it did great.

So why everybody sayin LM-22 is a must? It costs good 70 buks more for each tires, so I wouldn't want to waste it just because of trend

Thanks

 

Another question is
will 215/55 - 17 fit stock 17" rims of Touring 5AT?

I want more narrow tires for winter. The error for 215/55 going to be 0.2% only. Thats the width of the rim that worries me....