Electric Bikes - Slightly off-topic E-Quad

My 4 year old son has a toy ATV that he can drive around. It's never been that much fun for him because it gets stuck and spins out really easy.

Tonight, I removed the 6V 4Ahr battery and placed a 12V 12Ahr battery into it.

It worked pretty good. The quad now does a slightly less than walking speed and its got a fair bit of torque. Unfortunately, the cheap plastic tire still has no traction.

I think I might cut up an innertube and duct tape it to the tire. If it works well, I could look for a more permanent solution.

Has anyone here tried overvolting their kids toys?

yeah, I run my son's 12 volt Mustang at 22 volts and it goes 9.5 mph! Since we use it on the street, it doesn't get too hot. I've run my son's 6 volt quad (when he was real young) at 22 volts and after a bit, the motor fried (smoked for a minute before it fried). The cool thing about the Mustang is that he needs to start in first gear (low voltage) and he has to shift it to 2nd gear (high voltage) otherwise he's just doing donuts. Even in low voltage, he starts off doing donuts and he's already learned to countersteer to get it going straight. He's got a new powerwheels tractor for the off-road grass use and we can only use 18.5 volts because off road, the motor pulls more current and it appears there is some sort of thermal resistor. One day, I'll pull that out or better yet, replace the 540 motors with twin brushless motors from my RC cars and that'll allow him to go as fast as I dare let him. lol

Just turn a whole car his size into a RC and then he will truly be only able to go as fast as you want him to!