Details about K2
K2 are a Exotic Wheels.
Wheels are steering and carrying your Battle-Car. They can either be animated or static. Every wheel has a custom trim or even a custom tire tread. You can equip them inside the customization window in the wheels tab.
To get the K2 Wheels you can either open a specific crate with a key or trade with other players.
You can search for trade offers with K2 here.