2WD setting for normal road driving and towing in normal conditions
4 WD for off road towing/driving and in snow or ice .. best not to have it in 4WD in normal conditions as it will wear out the tyres and dammage the transmission!!!! unless it has perminant 4x4 then it has a special transmission that allows it.. best to read the hand book for advice or ask the dealer......
When running around without trailer I use 2wd on our LWB Shogun, unless road conditions are like last winter, in which case 4wd was used.
When towing I use 4wd. Why? 'cos that's what the handbook says to do and having towed the trailer (Equitrek Space L) in 2 wd by mistake one day and found the handling appalling I soon realised the error of my ways.