Got one for my 3 yr old, giving it to him tomorrow for his birthday! He's been riding a 24v (10mph) for a year. Can waaaiiiittttt to let him rip in the woods.
KornFed Kustoms my daughter was 3 1/2 when I got her a polaris 50 it comes with foot raisers she will probably be a little small for it but a year will go buy quickly and she will probably grow into it
It depends on his riding experience he will definitely grow out of it quickly but if you start him on a 90 he might get scared and not want to ride at all