2 6S 5000mAh in parrallel !!! That's very heavy, especially for a truggy geared for 100 mph

With your crazy gearing, I am surprised that the ESC blown before the tires ^^
Seriously man, a truggy is not design to go over 45-50mph in normal ways, next time try with a 11T pinion, the castle 2200Kv run good geared for 35-40mph, if you want more speed you need to get a bigger motor, in order to reduce the amp draw.
You are right, if the gearing is to small, the motor can overheat if the throttle is continuously full, but it would be with a 4-5T pinion !
Good luck for the next time anyway.