Effectiveness of toughness

Here's the background...

I switched to ret to level, and have found myself tanking quite a few instances as ret, just tossing on my tank gear and going for it.

But I realized I could probably spec better to help it. I'm looking at toughness, and trying to figure out exactly how much it helps, 10% armor, I can read, but I don't quite understand how that impacts mitigation.

I got this formula from wowwiki:

Armor Reduction

levelModifier = attackerLevel

if ( levelModifier > 59 ) then
levelModifier = levelModifier + (4.5 * (levelModifier - 59))
end
armorReductionTemp = armor / ((85 * levelModifier) + 400)
armorReduction = armorReductionTemp / (armorReductionTemp + 1)
if armorReduction > 0.75 then
armorReduction = 0.75
end
if armorReduction < 0 then
armorReduction = 0
end


but, damned if I don't really suck at math. basically, this is my spec I'm thinking about:

My Spec

I'm trying to figure out if it's really even worth it to go ahead and go down to toughness, or pick up something else somewhere else. like maybe kings, which could perhaps yield better results for me. Since threat is a little more concern for me, well maybe not, now that I just got my SoR.

If someone who is better at math can maybe help me figure out more or less how much mitigation that works out to, that'd be great!

P.S. In my gear right now, I have ~16k armor.
_________________
Kuripari Level 70 0/55/6 - Skywall US Horde

Not takin Thoughness is wrong, period.

It's probably the highest mitigation talent of the whole tree. And it scales with gear.
_________________

Uord - Prot Warrior
Darkworldie - Death Knight

Tanking... srs business

/shame

I shoulda known that, thanks though!
_________________
Kuripari Level 70 0/55/6 - Skywall US Horde

if you are going to tank as Ret you're going to be squishier anyway...if you're going to spec specifically to help tanking, you might as well go Prot.
_________________
better to tank in hell than DPS in heaven

That spec requires level 75, so I´m guessing that´s his level. That spec allows him to be a little less squishy when tanking, and still faceroll through quests. Seems like a good idea compared to respeccing twice a day :)
_________________
Kieras <- armory

Wowzers! that's still alot of math!

Surprisingly it does help explain it alot more though, and it's something I can work with.
_________________
Kuripari Level 70 0/55/6 - Skywall US Horde

Ok, so using those formulae I did some calculations on the amount of damage that Toughness mitigates. I'm not sure what "normal" lvl 80 plate armor levels are yet, but...

Between 20k and 30k the extra damage reduction you get from Toughness is between 2.4 and 2.2%

The reduction falls because of the "diminishing returns" of extra armor, but the time-to-live benefit still scales up with gear (from about 5.5% increase to a 6.5% increase over the same armor range).

In all, if you're looking for a hybrid or OT spec, the other damage-reduction talents are much better point-for-point. Toughness gives less than 0.5%/point, Imp. RF gives 2%/point, Shield of the Templar 1%/point and BoSanc 3% per point However, I don't really see anywhere else that you'd want to put the points, unless you were doing a PvP build, or not going deeper into the tree.
_________________