Disco 2 has a bit more space in the arches than a D1. With a couple of inches of suspension lift, you can get a 235/85 R 16 in there without too much trouble. (Pretty sure this is what Thermindor has / had on his)
Beyond this, I'm not sure... the only sizes I've seen fitted above this have been a lot bigger... (like 38" tyres) and that is a whole new hatful of spiders !
