First I want to say that you can go with this "go-kart" on meadow, mud, sand, mud and asphalt.
On the lawn turns before by the rear wheel. But it can go well anyway.
Our son (4 years old) fits perfectly to it and it was also easy to assemble.
What we find very good, is that as soon as you no longer occurs to the freewheeling is automatically activated. ie the pedals do not turn with it when it thunders downhill. I do not know how it is in the Kettcar's, but I suspect that there you must set the switch to idle, which our would slightly overwhelmed at the beginning.
Now he has to get out and drifts around so diligently. Now we wonder whether there is already spare hard tires?
Oh, and the tires are also better than air-filled, because you can prevent the problem of a flatfoot.
MFG