Answered: Pneumatics Tanks as Ballast?

[artsy.andrew]

Is it legal to have all 12 motors on a robot, and use empty pneumatic tanks as a counterweight with no other function?

[VEX_GDC]

No, this is not legal. Let’s take a look at R11, quoted here for reference and bolded for emphasis:

<R11> Robots may use either:

Option 1: Up to ten (10) VEX EDR motors or VEX Servos (Any combination, up to ten) and a legal VRC pneumatic system. (See R18)

Option 2: Up to twelve (12) VEX EDR motors or VEX Servos (Any combination, up to twelve) and no pneumatic components, excluding pneumatic tubing.

Pneumatic tanks, even if they are empty, are still considered pneumatic components.