Bear raid tanking discussion

[Shamago]

Everybody agrees on the 415 being an important safe number. The 28k I'm really questionable about. I don't think its safe to be counting on inspiration or the shaman equivalent to be there. What is the total amount of armor needed to hit the 75% armor cap against raid bosses? Does anybody know this exact value?

http://www.wowwiki.com/Formulas:Armor

Armour damage reduction = (AC / (AC - 22167.5 + 467.5 * [attacker's level]))

Same page puts 35886 at 75% reduction vs a 73.

So about 35.9k.