When our team of engineers began creating the original 3-across car seat back in 2006, they did extensive research to learn what fit would be the most suitable across a wide variety of vehicles. Since then, we have continued to monitor different vehicles to maintain our original 3-across fit.
The most popular question our team is asked is “can I fit Radian® 3-across in my vehicle”. There is no definitive answer but we have some guidance to help you determine if 3-across will work in your vehicle.
To start, you’ll need a minimum of 52 inches of physical space across your back seat to fit Radian® 3-across. This doesn’t take into account vehicle seat shape, contours, or seat belt locations. If possible, we always recommend doing a fit test with the seats to ensure you can install 3-across correctly. Start with the center seating position, and then each outboard seating position.
Other things to consider are whether the Radian® will be forward-facing or rear-facing, and where the seat belts are located. Rear-facing Radian® require space to fit because of their recline angle so you’ll need to make sure that the driver and passenger can still sit safely and comfortably in front of rear-facing Radian®. Check out the Diono Angle Adjuster if you need extra space between the front vehicle seat and a rear-facing Radian®.
Seat belt location can also play a role in 3-across. If you have a center seat belt buckle and an outboard seat belt buckle that are right next to each other, it can sometimes be difficult to get a correct install with one or both seats. This is why it’s really important to do a test fit if possible.
Are vehicle headrests needed? Yes! All forward-facing Diono car seats require that the top of the car seat be supported by the vehicle headrest or vehicle seat back. If your vehicle’s back row does not have three headrests on the back seat, or there is not enough support from the vehicle seat back, you will not be able to install three forward-facing Radian® seats as instructed in the manual.
Lastly, read your vehicle manual! Some vehicles may not allow a car seat to be installed in certain seating positions which would mean that 3-across would not work.
If you are still uncertain, we recommend checking out forums such as Car Seats For The Littles and asking other parents and caregivers if they’ve successfully installed Radian® 3-across in the same make/model/year as your vehicle.