Tier 4 is an upgrade in which a player gets 10 vehicles to Rank S (250 kills). Tier 4 has a lot of good upgrades for vehicles. The upgrades are:

a multi-missile launcher for Artillery

a chaingun for SpeedBoat and Jeep(to be moved soon)

a heat cannon for Destroyer

a high-explosive cannon for Vortex

the Volatile LC for Shadow

a 20mm machine gun for ATV

dual HEAT shells for BattleTank

and a high-explosive chaingun for HelicopterCarrier.

35mm Minigun and Lock on Air to Ground Mİssiles for Attack Helicopter

Railgun for Jeep and Tank Gunner[Not yet, confirmed to be added