Repost from the Ideas section, TLDR New Units/mechanics and changes are highlighted.

Currently the only weapon in the game built to take down tanks is the anti tank gun, as well as the MBT, who both have the Armor Piercing Modifier. This makes the MBT undisputed, uncontested cornerstone of military power in the late game with pretty much no counter other than air units, other MBTs or absolute swarms of other gunners. Proposition to rebalance tanks being broken: expand the technology around tanks slightly for more flexibility and counterplay. 

Some new and existing units receive [High-Explosive] modifier: +11 Combat Strength vs ALL Vehicles

ERA 5 TECH: Continuous Track (Requires Combustion Engine, Leads to Assembly Line)

Unlocks unit: Anti-tank Gun (Heavy weapon, Armor Piercing, 53CS). Upgrades From Howitzer

Unlocks Unit: Heavy Tank (Armored Vehicle, 3 Movement, 3 range, 54 Combat Strength) Cost 1 Oil, 3 Iron

ERA 6 TECH: Assembly Line (Requires Continuous Track, Leads to Composite Armor)

Unlocks Unit: Medium Tank (unchanged)

ERA 6 TECH: Propelled Projectiles (Requires Trench Warfare, Leads to Insurrection Theory)

Unlocks Unit: Rocket Launchers (Gunner, High-Explosive, 6 Movement, 6 range, 52 CS)

ERA 6 TECH: Computing 

(Same unlocks as current)

Unlocks unit: MANPADs (Gunner, High-Explosive, Anti-Air 6 Movement, 8 Range, 58 CS)

Cruise Missiles and Helicopter Gunships should also gain [High Explosive], and also nuclear missiles for the hell of it.

I totally agree.