Not sure of the size but wheel bearing nuts are not suppose to be tight, just snug so bearings can spin freely with minimal play.
This is why these nuts will have a "keeper" of some sort so they don't unscrew.
On the 4x4 model there is a slot in the threads and a small woodruff type key is inserted, this key must be pulled out to unscrew the nut, often you need to tighten nut slightly to release pressure and remove key.
On others the nut will have fingers that stick out and after tightening a cotter pin is inserted thru the shaft
Or a nut cover with fingers, this fits over the nut and cotter pin is installed
Both keep nut from unscrewing
But for any of these, the wheel bearing nut can be removed or tighten with a pair of channel locks, pipe wrench or vise grips once the "keeper" is removed.
On the '98-'00 ranger 4x4s the wheel hub has to be replaced as a whole unit, it has "life time bearings", lol
Read here:
http://www.therangerstation.com/Magazine/spring07/98_00_Ranger_hub_bearing.htm
Not sure if this applies to 2WD models