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I bought them after the 'beast from the east' (cheap ebay deals) and have used them 3 times for my commute since then, all this year. Which basically meant my wife and kid had a car to get about when it was snowy/icy. I imagined I'd use them about 5-8 days a year, which seems fairly minimal, but when you have one car it just gives a bit of peace of mind. On heavy frost and thick ice (commute has a fair bit of it) they're brilliant and being Schwalbe Marathon, I expect them to last forever.
Schwalbe K-Guard winter spike 700c x 30 is £15.99 at chain reaction: https://www.chainreactioncycles.com/schwalbe-winter-spike-road-tyre-k-guard/rp-prod118113
I've not used this particular tyre but the 'Marathon' version are great.