It looks like you're new here. If you want to get involved, click one of these buttons!
Results of disembowel testing | Knight limb counter | GMCP AB files
Yeah, the base is 90/90 (since you can't see the actual stats of armour any more, that's 51/51 in the current display), and forging can add up to +2/+1 or +1/+2, then runes can add +7/+7. So the max with runes is 99/98 or 98/99 (in the current display, probably 56/56 either way), max without runes is 92/91 or 91/92 (probably 52/52 either way).
How much damage reduction would that give though? best guess acceptable.