For 285's you will definitely need wheel spacers. I went with 1.5" to make sure they were comfortably clearing the bolt...plus I like the look of tires sticking out hahah. For 265's some people have gotten away with no wheel spacers. Trial and error really.
'15 JK 2.5" lift on 35's
'06 WK 3.5" lift on 33's (Sold)