I'd suggest that you find 16" rims for an '81-'87 3/4 or 1 ton 4 wheel drive, they will fit without rubbing. The reason I suggest 16s is that there aren't any 15" radial tires with the rating for the weight of your truck, but there are plenty of 16s that will work. As far as a "radial tube" goes, most modern radial tires are made to run tubeless, only a few European heavy trucks (20" rim) still use tubes with radials. Most tire shops I know of, including the one I work at, don't carry tubes for radials. Even tubes for bias tires are hard to get in my area, as most shops don't stock bias tires anymore. I wouldn't run a tube in a tubless radial, seen too many blow out from having a tube in them, too much internal friction.
