Don't need to change this summer with Nokian WR - hehe
Yup, I finally decided on the Nokian WRs too for my all seasons (Nokian RSI for winter). Now I do not have to worry about being caught off guard by the snow. How coincidental it is that when I switched to this tire just this March 17, the following day Calgary weather decided to dump some snow on me. No worries

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And everybody else is right with their suggestions on the timing. I am only learning now how the seasons changes here in Calgary.