Most "kids" shouldn't be allowed to ride four wheelers without adult supervision. I've known too many who have almost killed themselves on them. Myself included. 16 and older I guess could ride one, since they're allowed to drive 30,000 pound missiles down the road.

I have been in a bad four-wheeler wreck myself. I was 16 and I left half of my skin on the road. Couldn't move my shoulder for about a month after the wreck and still have pain and scars to remind me of it.