On Ih8mud.com under wheels and tires a guy is selling a really nice set of 285/16 Geolanders with 8M on them for $450 for the four + a good spare included. they have a road hazard warranty and he is in San Fenando Valley area.
I helped Johnny C find a tire in that size over on mud. That is a VERY common tire size for the non lifted 80's. there are a lot of guys over there that have them. Look through the for sale adds and you should find some success.