When children outgrow their rear facing seats they should be buckled in a forward facing car seat in the back seat until they reach the upper weight or height limit of their car seat. Check the seat owners manual andor labels on the seat for weight and height limits.
Child Safety Seat Wikipedia
Height or weight limit for rear facing use. Once your baby has reached the limit for their rear facing only seat often. When your child has reached one of these limits they are too big for the rfo seat and must move into a larger car seat. Have a 5 point harness that attaches at the shoulders at the hips and between the legs. Even if your childs legs are touching the seat back or they cry when rear facing you should still keep your child rear facing until they reach the rear facing weight or height limit of the car seat. A convertible or all in one car seat should be used in the rear facing position for babies who outgrow infant only car seats. After outgrowing the forward facing car seat use a booster seat until seat belts fit properly.
Weightis 30 to 35 lbs total heightis 28 to 35 inches. For most seats a child is too tall for rear facing when the childs head is 1 inch below the top of the seat. Likewise most forward facing seats on the market have a minimum age of 2 years. Picking a car seat with both a high height and weight limit for rear facing as well as generous room for the legs will help ensure your child stays rear facing for as long as possible. Torso heightis when there is less than one inch from the top of the childs head to the top of the carrier. Many have higher limits in rear facing weight up to 4050 pounds and height than those of rear facing only seats a feature that makes convertible seats ideal for bigger babies and toddlers.
Most convertible car seats have rear facing weight limits of 35 to 50 pounds so most kids can ride rear facing until age three to five. Once in a convertible seat parents should keep children rear facing until they have reach the height or weight limit for the seat. With most rear facing car seats there is a maximum weight of 40lbs. Use a rear facing car seat until your child is at least two years old and up to the highest weight or height limit of the car seat. Kids usually outgrow rear facing seats in height. These seats are designed to be carried outside of the car so they typically feature lower weight and height limits.
This is usually the standard across all types of rear facing car seats unless stated otherwise by the car seat manufacturer. Rear facing infant seats still provide the best fit for newborns. While its technically legal to turn a child forward facing at this age its better to wait. Some infant rear facing car seats have a low weight limit of 22 pounds that make extended use almost impossible.