burning out motors

this i what Brian's calculator says for my setup

Differential Ratio: 3.3076923076923075
Transmission Ratio: 1.640953716690042
Other Ratio: 1
Spur Tooth Count: 49
Pinion Tooth Count: 20
Total Voltage: 16.8
Motor KV: 1853
Tire Diameter (inches): 5
Tire Ballooning (inches): 0
Motor Current Draw: 0
Motor coil Ω: 0.0092
Spur/Pinion Ratio: 2.45 : 1
Total Ratio: 13.29804 : 1
Tire Circumference (inches): 15.71 inches (398.98 mm)
Total Motor Speed: 31130.4 RPM
Vehicle Speed: 34.82 mph (55.94 km/h)
Estimated Adjusted Speed: 33 mph (53 km/h) - 4% loss
Effective KV Value: 1853
KT constant: 0.73 oz-in/A