^^^ i don't think it protects alloys... it just doesn't damage them.
I might see how this could work on
fully snow covered roads... but i wouldn't count on this lasting once this contacts pavement...
Edit:
According to tirerack.com (
http://www.tirerack.com/accessories/autosock/autosock.jsp), this is exactly the case...
QUOTE
Comfortable While Driving – Maximum Speed 30 Miles per Hour (mph)
AutoSock does not produce the loud rattling nor the bumpy ride associated with snow chains. AutoSock does not damage the vehicle structure or alloy wheels and are approved for speeds up to 30 mph (50km/h). Nevertheless, the driver's speed should remain appropriate for the weather and road conditions.
In What Sort of Conditions Can AutoSocks Be Used?
AutoSock will greatly enhance traction on snowy or icy surfaces. It is recommended that AutoSock be removed when the vehicle returns to roads where no snow or ice is present. Driving on dry or wet roads is not recommended as it increases fabric wear considerably.