I don't live where chains are normally (or legally) required, but there
certainly have been times when a little more traction would have been nice.

I stumbled upon this video that shows some alternatives to chains.
(Warning: it's 20 minutes long)

https://www.youtube.com/watch?v=chrLCKzAVVg

The Snow Socks look interesting; there's even a similar product made by
Michelin, which I guess gives the concept some credibility. There are also
individual "traction strips" that go through the wheel and wrap around
the tire perpendicular to the treads.

My concern with the sock type is that all the installation instructions seem
to indicate that you need to move vehicle forward just a bit to finish
the installation. Maybe just rolling the *wheel* itself, i.e. slipping it
a 1/4 turn on the ice, is enough, assuming you don't spin the sock right off
of the tire. Of course, everything works perfectly in the video.

Has anyone tried any of the "chain alternatives", especially to get
out of a stuck situation where the tires just spin and/or slide
sideways?