Are 5 tank champions viable?

[Thalais]

I always wanted to see how this would play out.
My idea was to have the following 5 tanks/Tanky DPS:

1. Galio (mid)
2. Garen (top)
3. Rammus (jungle)
4. Mundo (bot) {damage}
5. Amumu (bot) {support}

Items:
Warmogs
Thornmail
Force of Nature
Boots
(Main Item)
(Main Item)

The goal is to make the entire team balanced around survival and defeating people over time than quick bursts. Since they are already tanky, they should lane well and with Range not being an issue for Bot as Mundo can throw his cleave and amumu can stun, I think bot lane is OK and difficult to gank as they wont blow up as easy as other champions since they are tanks/tanky dps.

PROS:
1. Survival
2. AoE potential
3. Ganking is medium-high
4. Average damage

CONS:
1. Slow Lane for Bot
2. Burst is low-medium
3. Item heavy early-mid game
4. Longer game (most-likely)

[Deleted]

Rather get Jarvan/Leona, Jarvan/Taric, Blitz/Alistar or something like that for bot lane since you´ll actually win lane with that and you can still build pure tank. I think this could actually destroy a lot of people in normals and even be quite useful in ranked 5s as nobody will be prepared for it. Not really viable in pro play but still pretty fun.

[TEHPALLYTANK]

You could just build some of them as damage(AP galio and mumu, AD garen). Thornmail would be a bad choice if they are AP heavy, deciding the items ahead of time like that isn't the best idea.

[Duilliath]

Take Cho'gath, Amumu, Galio, Malphite (3 of 4) for top/mid/jungle.

As said above, Leona + Jarvan bot.

[Thalais]

Leona and Jarvan is a good bot, may look into it

[TFTCDave]

You would have to win early IMO. If you didn't your scaling would drop off and late game carries would just build penetration and blow you out of the water. I've actually played against a tank team with some friends awhile back and we won easily. If you get behind even a little bit it's GG, because once they get a few kills up on you, you're going to be unable to get tanky enough to deal with most character's scaling.

For example against a normal team:
Kayle (top)
Vlad (mid)
Olaf (jungle)
Caitlin (bot)
Janna (bot)

and that's just one example. I'm not saying it couldn't work. I'm just saying it's not bound to be effective in the long run, especially at higher levels of play.

[Toxigen]

With the buffs to armor pen, not sure if this is really viable anymore.

[Isrozzis]

early to midish game yes. You will be able to cc/bruiser people to death.

Late game no, the ad carry on the other team will just tear you to pieces. Especially if there is a vayne or something.

[JimPaladin]

If Thornmail wasn't such a terrible item, it would work, but late game AD would be too much of a problem, unless you ended the game fast.