I am comparing it to our Graco MyRide65. My DD is right at 30" and 20lbs.
Here are both seats. Radian on left, MyRide on right. (Radian does not have boot on yet.)

With the boot.

Clipped into the Radian. You can see how much more height she has left.

Clipped into the MyRide. Still lots of room!

Installed in the car. I have a 2008 Mitsubishi Lancer.


Here you can see how the height of the seat does NOT get in the way of viewing out the rear windshield.

**I installed the Radian in the center position with shoulder/lap belt. I have not finished installing it or have it checked yet. I mostly just popped it in the car quickly to take pictures**