depends what you want to do with your truck!
A 285/75 will fit no problem but make sure you have the right rims! There are two stock steel rims, one thats 5.5 inches wide and one thats 6/7 inches wide! If you have the 5.5 inch rims then you should only fit up to a 7.50 or 235/85 maybe a 245/75. To go larger you need to upgrade your rims too, either with standard LR steels or aftermarket rims. Standard rims (7 inch) are found on 110s and you can also fit disco steel rims too (I have these on mine), after market rims are things like 8 spokes or modular rims. Once you have upgraded the rims then you can go up to 285/75 with no real problem. You will have to adjust your steering bump stops, but thats really easy.
If your looking for decent articulation of your axles then I would suggest you get a suspension lift! 2" lift would suffice!
Depends what you want to do! Would help if you told us what you intend to do with yer rig? rock crawling, mud plugging, street cruising (heaven forbid!!)...