We have them on our truck and would not be without them. We initially put them on because it would have been very hard to get chaines to fit between the tires and the plastic fenders we have on the rear, and like everyone else I don't like to lay on my back in the cold slush.
What I never thought about was the added safety they provide when you only need then for a mile or just a few blocks. I think it was November 6, I was going thru Waukesha, WI and it had just hailed for only about half a mile. The road was solid ice and cars were sliding every which way. I was able to slow down, maintain control, and drive right thru it without even breaking a sweat.
They are great when traveling over moutain passes with snow or ice when the lower elevations are dry. Drive up the hill and it starts getting slick, just flip the switch. Drive over the top and it gets dry again, flip the switch and you have just saved yourself an hour and a lot of cold muscles.
We have the ON-SPOT chains which cost around $1400. for the system, and about $600. labor to install. You can order them on just about any new chassis and save a bunch of the labor cost.