Dangerous, for the common driver. They are really dangerous on normal roads in the wet. They are fine in the dry.
I have done my share of driving with “loss of traction”, and have also been caught out with Blizzak MZ-03 tyres on. They are fine in the dry, feeling like a under inflated tyres (probably due to the soft rubber and high individual tread pattern), but put a tiny layer of moisture on the road and these tyres suddenly become very loose. Great fun for any drifters, but very dangerous for a family and/or inexperienced driver.
Many cars in New Zealand get imported with these tyres, some people know they suck and sell them on. Please warn the buyers! Unless you want deaths on your hands. I would never use these as road tyres again!
There is lots of debate on these tyres being responsible for deaths already, but statistics are
often not valid, until someone makes them. What I mean by that;
The reason there in no deaths attributed to this type of tyre is probably only because the type of tyre involved in an accident may not be recorded, only the tread depth.
See some links for more debate on it here, here and here. [edit and here 3rd July 2008]