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Failure. Brake setup problem?

Half of 250 is 125 feet. I have access to two 160 Super Cubs, one with Thrustline and VGs and very little else - a lightweight 1950 model converted. And for a while I had access to a 180 CC Cub. None of them would get off the ground in less than 250 feet. My J3 with Stroker takes 190 feet.

I admit to being not the world's best Cub pilot, but technique alone is not enough to cut a takeoff roll in half - unless we are talking about those guys who raise the tail and sail down the runway flaps extended to 70 mph. I am not one of those.
 
That begs the question whether the brake energy is different with different tire diameters
No. The braking energy dissipation is a function of airframe mass and speed only. More brake disk friction is required with bigger tires, but it operates through fewer rotations. Same energy dissipation.
or is the energy a factor of the rotor diameter?
Again no, except that for a given rotor configuration, larger rotors have more mass and can absorb more energy for a given temperature rise.
If the latter what role do large diameter tires play in braking?
For a given ground-tire friction force, the force directly acting to slow the airframe, the larger tire transmits more torque to the brake disk.
 
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