What is the smallest (in height) quad that is made?
And, how old do you have to be to ride it?
I'm in CA...

 

1) The smallest quad I was able to find was the Suzuki LTA50. It had the shortest inseam length I could find.

2) According to the IDIOTS at the CPSC, the child must be 6 to ride any quad. When purchasing a 50cc ATV, tell the dealer your child is 6 or over, otherwise they might not sell it to you. There is no age law in Ca. Realistically, the starting age is up to the parent, based on size, maturity, attention span, etc. I started my son at 3, but chased him around for a bit with the kill switch tether in hand. The biggest issue I had was attention span; it's really easy to distract little ones.

 

E-ton sells a pretty small quad called the viper jr.Don't know a lot about it but it is quite small.Features a 41cc engine and a remote kill switch which might come in handy with a little one learning to ride.Check out http://www.etonamerica.com/ATV-RXL.htm