Full disclosure, never owned a tang, but did a lot of reading about them. Common theme usually is bigger tank is better. With that said, total volume of tank is only 1 part of the equation, length of a tank being the other one. It is better to have a 5 foot 110 gallon tank than 4 foot 120 gallon tank as an example. That extra foot of swimming space makes enough of a difference, as tangs swim length of the tank whole time.
Bristletooth, Kole and Yellow tangs seem to need least amount of space. You can always get a juvi tang and keep it until it outgrows your tank. Then either re-home it, or upgrade your tank haha. I am sure others that actually had tangs will chime in with lot more specific info.
PS: Great site with info on each species of fish, their temperament, min size tank and so on:
https://www.liveaquaria.com/category...ons?c=15+43&r=