Anonymous wrote:OP here. The seats are Sunshine kids radian seats and they are supposed to be safe for kids up to 65 pounds or 80 pounds, and 4'4", with the five point harness. I just have no idea at what age kids "typically" reach those two points, or if it would be just plain cruel to expect him to sit in one after a certain age. I do think tests show that the 5 point harness is much safer than using the car seatbelts -- as long as the height and weight are ok.
My dd sat in the Sunshine Radian 80 until she was 9 1/2 yrs old. According to her last check up she was in the 50-60% range for height and weight. Now, she did not sit in this seat all of the time. She usually sat in a high back booster but we have one position in our vehicle that only has a lap belt which then requires a 5 pt harness seat. The proper saftey restraints are non negotiable in our vehicles. My kids know it, their friends know it and it has never been a problem. The older kids love the Sunshine Radian because it looks like the seats that the Nascar drivers sit in. They learnt at an early age how to answer any teasing about sitting in a harness seat. thinking back our kids sat in the Sunshine Radian, as their primary seat, until about age 6. But on an as needed basis until 9 1/2.