Not sure what difficulty you are running on. I have mostly been main tanking the dragon on Hard and I have found it quite manageable -- easier than tanking Skeletons on Hard anyways. My tank's stats are significantly lower than what you posted, so maybe you are running it on a higher difficulty than me.
18 Paladin, 2 Fighter
82 CON
225 AC
5100 HP
333 PRR
183 MRR
80% Fire Absorb
98 Fire Resist
I wear Bracers of the Glacier for this raid, with the permanent Fire Shield: Cold effect. The dragon debuffs the tank's Fire Absorb, so it's crucial for me to get this Fire Absorb as high as possible before stepping in. Otherwise your absorb goes negative and you take a lot of dmg.
I tend to stand in the center of the arena. I don't mind the fire elementals or their ground circles - they really don't do anything to me.
The dragon has a knockback & a knockdown special attack. These can be prevented with Shield Block. This is really useful to prevent from being knocked down all the time. I typically auto-attack with melee (mostly to prevent the AOE fire dot on the party and also to proc my +1000 temp HP), and then Shield Block when I see the dragon's animation starting to do the knockdown special attack.
I have 310 Healing Amplification and 660 Positive Spell Power, with 35% Crit Chance and 66% Crit Multiplier. This allows me to cast Renewal on myself for plenty of self-healing. If I keep Renewal up on myself, that's enough to handle any damage I take while tanking for the ~25 mins it usually takes for the raid.
I also have 16 charges of Lay On Hands, which self-heals for over 5k HP. I sometimes use Lay Hands if I get knocked down and fall below 2k HP, just to quickly get back to full HP.
I have noticed that standing in the blue Dead Magic Zone will dispel my permanent Fire Shield from Bracers of the Glacier, so I try not to stand in that zone when tanking. I have also noticed that when this happens, I need to re-equip the Bracers to get my Fire Shield back on -- merely stepping out of the blue dead zone doesn't automatically bring it back.
Swivven / Swivvirtue / Swivventure
Guild Officer of The Silver Legion
Cannith server