hello brian...well if the hexes dont fit snug in the rims then there will be movement and this movement of the hex will also cause a movement on the shaft and so cause the nut to loosen against the wheel, every time the shaft moves it will gradually undo the nut in the undo direction. u need the hexes to fit well or this will continue to be a problem. some manufacturers will provide too much clearence to there hexes and cause this problem, i have eleminated this problem by custom fitting the hexes to fit the rims. take your wheel, drive shaft, hub off,, set up as it is on the car hold the hub with one hand and try to turn the wheel with the other you will be able to "feel" the play in the system. this play will loose ur nuts. also play in the drive pin against the hex can be a problem. yes i know this is an old thread but if u still get this problem it can be a pain in the arse so just wanted to help as ive looked into this problem and solved it by tight fitting hexes with tight tolerences.