Those automatic chains probably won't be sold to the general motoring
public in the US due to liability issues - - it's hard enough to get a
professional driver to use them correctly (IIRC only at speeds up to 35
MPH). They sure don't want the lawsuits that are bound to happen when
someone tries to engage them at 70!

I worked at a place that ordered several trucks with these - - they lasted
about two weeks before they "exploded" by drivers using them at 50 + MPH.

Gary