The attributes for dragonhide armor are pretty vague. I see no reason armor made from a dragon's hide has to be heavy/plate. I don't see how dragon hide could be clothing (AC 0), though.
I am looking for guidelines for all hides, not just dragons. But, taking a shot in the dark i get a nightmare; leather armor is AC 2, Adult black dragon has a natural AC of +18. 2e DnD says armor made from a dragon's hide is 4 less AC than when the dragon was wearing it. That would make black dragon leather armor AC 16 or at least ac 14 (2+18-4 or 18-4). That is too much. I think a dragon's hide should also provide some resistance to the same kind of damage as it's breath. A wyrmling white dragon (the least of the dragons) has a natural AC of +2. I think armor made from a great wyrm's hide would be better than from a wyrmling's hide.
I am looking for guidelines for all hides, not just dragons. But, taking a shot in the dark i get a nightmare; leather armor is AC 2, Adult black dragon has a natural AC of +18. 2e DnD says armor made from a dragon's hide is 4 less AC than when the dragon was wearing it. That would make black dragon leather armor AC 16 or at least ac 14 (2+18-4 or 18-4). That is too much. I think a dragon's hide should also provide some resistance to the same kind of damage as it's breath. A wyrmling white dragon (the least of the dragons) has a natural AC of +2. I think armor made from a great wyrm's hide would be better than from a wyrmling's hide.