Psamathe wrote:Do studded tyres actually help on black ice ? I'd have imagined that the studs would provide extra grip by digging into the surface a bit and that resting on a hard surface they cannot dig into they might even give a lower surface area in contact with the surface. And I'd guess that black ice is hard enough not to allow studs to dig-in.
That said, I've never even seen studded tyres so may be completely mis-understanding how they provide extra grip.
Tyres provide grip by moulding around the minute imperfections in the road surface.
Tread, and studs, provide grip by causing the soft surface to mould around the tyre/stud.
So they can help - to the extent that you can just sail over some black ice - but if it's sufficiently thin then it will still be slippery, but you'll be breaking it up, so there will be more traction than otherwise (always assuming you don't grab the brakes and lock the wheel in a position where there are no studs)