I think they are the same width, the offset may be slightly different but not much.
The biggest tires I have run on them are 285/75. They seem a little "sucked in" around the rim, and I think that looks a little funny.
The biggest tire that looks good that I have run is the 265/75.
If you want to run 285/75 or 305/70 then I would suggest getting at least an 8" rim.