Originally Posted by JohnVidale
Driving on ice and snow in summer tires does not automatically result in an accident and megadeath. Yes, one is safer with snow tires, even safer with chains, safer still driving a Hummer at 5 mph, but driving in snow on summer tires can be fine and half the drivers are doing it.
Anything can be fine for a while. Driving without seatbelts on is perfectly fine, until you crash. Hooking up with random girls without rubber is also fine until your balls start to itch. Even Russian roulette is fine until you gets your head blown out.
So it is pointless to say "driving in snow on summer tires can be fine and half the drivers are doing it." (By the way, care to back up that "half" by an actual study?) The fact is that the decrease in grip level is significant when you run summers on snow, and it will significantly increase your chance of crash. Does that mean that you are guaranteed to crash on the first snow day of the winter? Anyone who thinks that needs to learn the concept of probability. But the fact that certain probability is below 100% doesn't make it unlikley. You may be in Seattle and have little need for dedicated snow tires, but running summers all year long in NJ is really pushing your luck.