Anonymous wrote:3.5
+1, it might even have been closer to 4 for us.
The main reasons I know of for switching earlier than that are (1) if the child gets severely car sick, switching to front facing can address this issue even though it's not the ideal position in the car, (2) hit the weight max for rear-facing earlier.
One thing our pediatrician told us is that height on it's own is not a reason to turn them around, unless their upper body is outgrowing the rear-facing seat to the point where their head can't be properly cradled in the seat (if it's over the top of the seat, you lose the main benefit to rear facing). But having longer legs that are up against the back of the seat is not, by itself, a safety risk. The main concern is head injury, not leg injuries, and it's better to keep your kid rear-facing as long as possible to prevent head injuries.