I spaced-out
to improve handling a bit, wider is more stable, and the stock width is a bit narrow to me. I run close to a stock tire and don't feel it is too much stress on it. The spacers are cheep compared to a new set of wheels and I like the Explorer Limited rims I am running now. I am sure there is a bit more stress on all the steering stuff, bearings, springs etc., but these are truck components and made stronger.
I ran spacers on a wheeler, wider is more stable, probably a good idea as you lift higher, and it allowed me to run wider tires without rubbing or buying new rims. That said I also had one ton axles to take the extra abuse. Large wheels on small axles are going to cause more problems and wear.
If you think spacers are going to come loose then you should also be torquing your wheels frequently. I have not had them come loose once torqued and then retorqued properly.
Spacers less than 1 1/2" will require you to trim wheel lugs. Then you are stuck with them or get to install new lugs. The wider you go and the larger tire you go with probably means more parts and repairs over the miles. Well, unless you spend the money up front to go big enough with the running gear so it will hold-up.
Wider also cuts the spring rate. The extra length of the torque arm gives 1 1/2" spacers about 7% more torque against the front T-bar spring or reduces spring rate that much. 235lb "A" T-bars become 217lb.
I feel in both cases my old wheeler and now with my Ranger that they helped improve what I was after, stability and were much less expensive than new rims. You got money to blow on rims get the backspace or offset you want in the rim.
I recently researched this before I put them on.....................working on the book now.