Tanks are burst damage dealers and not actually tanks. Though they are primarily for damage the Dwarf Tank is still a very resilient unit that can tank on the frontline better than almost any unit in the game, the reason why I say they are not actually tanks is due to them performing better as a support behind Mechsuits than they are on the frontline. The damage put out by a tank before it runs out of ammo is a lot and they may not be as tanky as the mechsuit they still serve as a strong frontline unit.

Research for Tanks unlocks at academy level 3

Tier 1: Fitness Training – Flat health increase, leads to Silver Tanks
Tier 2: Combat Training – Flat damage increase, leads to Concentrated Firepower, which increase the attack speed of Silver and Gold tanks Gatling gun attack speed by 50%
Tier 3: Expanded Ammo Capacity – increases the ammo held by tanks by x%, leads to Advanced agility training which increase the attack speed of tanks by 10%
Tier 4: Basic Fitness Training – increases the health of tanks by x%, leads to Gold Tanks
Tier 5: Building Proficiency – reduces the time to produce a tank by x%, leads to Training Discipline which reduces the gold cost to produce a tank by 20%
Tier 6: Advanced Fitness Training – increases the health of tanks by x%, leads to Rifled Bore which increase the damage of Gold Tanks flamethrower by 20%
Tier 7: Garrison Training – increase health and damage by x% while defending a garrison, leads to Field Training: Tundra, which increases damage and health by 20% when fighting on snowy battlefields
Tier 8: Training Discipline – Reduces the gold cost to produce tanks by x%, leads to Brutal Efficiency which reduces the rare resource cost to produce a tank by 20%
Tier 9: Elite Combat Training – increase tank damage by x%, leads to weapon research, which increase damage of tanks by 20%
Tier 10: Lethality – increase the critical strike chance of tanks by x%, leads to Survival Training which reduces damage tanks take by 20%
Tier 11: Superior Ammo Capacity – increases the ammo held by tanks by x%, leads to Elite Agility Training which increase tanks attack speed by 20%
Tier 12: Elite Fitness Training – Increase health of tanks by x%, leads to Weapon Refit, which makes it so Silver and Gold tanks side arms do not consume ammo (side arms are Gatling gun and flamethrower.)