Best guess specs after a small amount of google.
SPECIFICATION
Type Gear Motor
Protect Feature Totally Enclosed
Brand Name BRINGSMART
Construction Permanent Magnet
Continuous Current(A) 750MA (additional specs say 1 amp so that would mean your supply has to be at least 4 amp with some extra as a margin for best operation.)
Usage Home Appliance
Model Number JGA25-371 With Encoder Motor
Commutation Brush
Efficiency IE 1
Certification CCC,UL,ROHS,ce
Output Power 4W
Torque 0.5-8KG.CM
Usage Micro dc motors for toys, DIY motor
Speed(RPM) 18-1930RPM, choose one speed (gearing dependant)
Voltage(V) 12V
Encoder 3.3-5v Hall
Signal feedback A circle of 11 signals
Diameter of whole wheel 65mm
Diameter of motor shaft 4mm
That would indicate you are operating the drivers at almost max spec.
Bob.