I must say that when you're stuck in mud up past the edge of the rim it does in fact help to turn off traction control (ask me how I know ). Other than that one instance though I have yet to turn off trac when dealing with snow/ice/rain or whatever. Perhaps in instances when you want direct acceleratory control of the front wheels with no power loss (i.e. stuck in mud and racing) it would be better with trac off but I'd say for the most part it's best left on.