I have never lost one,(although I have heard of it happening) but I do a LOT of 4 x 4 driving. After changing a flat and trying to tighten the nuts up with the wheel wrench in 2 feet of mud and then off-roading some more to get back to the highway on a couple of occassions a couple of the lugs got fairly loose. I had to retighten them. I figure theres no harm in having 2-3 on hand. This hunting season the torque wrench is coming with me because I have a tendancy to try and drive over everything and will most likely need to change a tire or two.