How long can I use the radian 3R, 3RX, or 3RXT rear-facing? June 07, 2021 10:59 Updated The Radian 3R series can be used up to 50 lb while rear facing. If you’d like to find out more about the Diono Radian 3R visit our store: https://store.diono.ca/radian-3r/ Related articles How long will my Radian 3R last? Can I use a seat protector with the radian R-series? Radian® 3R Manual - English Comments 0 comments Article is closed for comments.