What is the LATCH weight limit, and when should I switch to a seat belt installation?

Do not use the LATCH/UAS lower anchors when restraining a child weighing more than 15.9 kg (35 lbs) in rear-facing mode or more than 18 kg (40 lbs) in forward-facing mode — only use vehicle belt installation beyond these weights. You must never use vehicle seat belts and LATCH/UAS lower anchors at the same time, as using both together can cause slack in a sudden stop or crash. Always use the tether strap regardless of which installation method you choose. (Page 29)