Not wanting to be caught out again, I have just fitted Schwalbe Winter tyres to my Bob Jackson World Tour. These are the 700 x 30c studded tyres that are similar to the more popular Marathon Winters, but with about half the number of studs. Importantly they are available in 30mm width, the minimum width of the Marathon Winters is 35mm which most road frames won’t have clearance for.
Fitting on to Mavic A719 rims wasn’t too difficult for a wired tyre but I did need to use a lever and push the tyre firmly into the opposite rim recess for the last few inches to slide over the rim, but they seated nicely when inflated. They cleared my mudguards which are set quite close to the 700x32c Marathon Supremes that are normally fitted, but in snow rather than ice, I would probably want a bit more clearance so would need to adjust them slightly.
They roll as I would expect on ‘normal’ ice free roads, a bit heavy (805g each) and noisy but not worryingly so. On snow they are OK but don’t expect miracles - better than a road tyre but not as good as a 32c cyclocross tyre. However, on the remaining stretches of packed down snow and on the ice, of which there is still a fair bit around here, they were every bit as good as I expected, no problem starting, stopping or turning - you do need to be careful when you stop as I can envisage forgetting you are on an icy surface, putting a foot down and ending up in a heap on the floor. It’s also worth mentioning that they work well on loose gravelly paths as the tread is reasonable deep right into the shoulders and I would imagine would be quite acceptable for mild off-road use.
They are clearly a very specialist tyre, I wouldn’t keep them on throughout the Winter as their grip on the typical wet and greasy roads is not as good as good quality road commuting tyres, but they are certainly worth the twenty minutes or so that it takes to swap them on for icy or snowy weeks. At less than £20 each they are reasonable value for money despite knowing that they will spend much of the year hanging on the shed wall.