I bought Nokian Hakkapeliitta tyres with 240 studs last week. The grip is amazing. On my test ride I rode down a hill with packed snow and tried brakeing to full stop. The stopping distance was not much greater than on dry pavement, pulling the front brake hard enough I could lift my rear wheel.
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My advice is free of charge and of respective quality.
1982 Miyata 912
1998 Wheeler 5900 with front and rear air cushion suspension
2015 Canyon Spectral 7.0 EX