A: It's tough to ask a kid to move back to a booster after being told it's not needed anymore. It's a clear indicator that they're not a little kid any more.
But you should consider making the move. It all depends on how the seat belt fits on your son. The American Academy of Pediatrics and National Highway Traffic Safety Administration earlier this year changed their recommendations on car seat use -- both recommending more time for younger children in rear facing seats and altering the perspective on boosters.
The decision on whether a child should be out of a booster should not be based solely on age or weight, but on whether he or she can be safely restrained. The guidelines say: "The shoulder belt should lie across the middle of the chest and shoulder, not near the neck or face. The lap belt should fit low and snug on the hips and upper thighs, not across the belly."
Generally, the transition to that fit happens when a child hits 4 feet 9, the academy says. Even though your son is just an inch away from that, the figure is a ballpark. So, just go by the description above and decide whether the belt fits him properly or if he needs a boost.