Am I geared enough to tank x?

90% of the time, if you're asking this question, the answer is: Yes you have enough gear.

The real question is Does your group have enough skill?

Clearing all content in 3.0 is a matter of co-ordination and skill. There is only one encounter in-game that is a serious tanking gear check, and as a pally, you'll probably never do it: Sarth Duty with +3 drakes.

Sarth+3 is MT'd by a bear with 50k health buffed, or a DK with quite good tanking gear. Nothing else requires really high-end tanking gear. I tanked all content up to and including Malygos-25 without having reached the Superior achievement (IE: I still had level 70 crap on).

Benchmarks for Tier-7

Step 1: Vendor / DE / delete your level 70 crap. There's maybe half-a-dozen pieces in-game that are worth wearing at level 80, and only two outside Sunwell: Shadowmoon Insignia and Commendation of KT. Sunwell tanking plate is pretty crap, but just barely acceptable in a couple of slots if you re-gem it for pure +defence. If you're wearing plate from BT or earlier, you're doing it wrong.

Step 2: Craft enough Tempered Saronite and Daunting hands/legs to get to 535 defence.

You are now ready for heroics Blue gear & 540 defence is enough for Naxx-10.

Step 3: Craft a couple of BoE epics. Titansteel hat/boots/shield (or Engineering goggles). Get to 540 defence. Gem & enchant your gear.

You are now ready for a complete Naxx-25 clear.

Step 4: Once you've cleared Naxx one time, blow all your badges.

You are now ready for Malygos and Sarth+2 (roughly even difficulty).

It is perfectly possible to clear all 25-man content the same week you hit level 80, with nothing but crafted gear. I went close, but weekly reset was badly timed.

Sarth+3 requires that your guild gear up. You will probably not be the choke point - DPS, Heals and the Sarth MT need better gear than you.

Benchmarks for Tier-8

Ulduar-10 drops gear of comparable quality to Naxx-25. This means there's little point doing Ulduar-10 if you have full Naxx-25 gear, unless you do hard-modes.

The following is educated guesses based on minimal feedback from the PTR, and official design goals, as inficated by GC and other blue posts

• Ulduar-10 is designed for people in ilevel-200 epics (Herioc & Naxx-10 epics).
• Ulduar-10 hard-modes will be doable in ilevel-213 gear (Ulduar-10/Naxx-25 level gear) - you will not need to farm 25-man to do 10-man-hard-modes (no Sarth3D equivalent?)

Ulduar-25 is designed to require 25-man gear to clear.
Ulduar-25 hard-modes are designed to require you to farm the zone before you can do them easily.

Completing 10-man hard-modes in Ulduar will provide both training and gear that may be useful for the 25-man hard modes.