May as well toss in my tuppence for what it's worth..

I've always associated the term as being namely a referrence for military kilts due to their weight (the 18oz & older 20/22oz weigh nearly 4lbs or more), and both the durability of the material and construction to withstand the rigours of military life and essentially wear like iron, or a tank.. ie, "It's as heavy as.." or "built like.."

As "tank" in this instance is namely a military referrence, I have always associated/used the term w/ military kilts solely.. As opposed to using it as a general referrence for any hand-stitched 16oz wool 8ydr+.. Which in my personal experience and opinion do not wear as hard nor as durable as a military kilt.

And with the higher military rise, one almost feels like they are riding in the tank's turret "un-buttoned" when wearing one.. ;)

Also, being a veteran I rather prefer the term "tank" in referrence to military kilts.