New Radian Carseat or switch 5.25 year olds to boosters?

We are carpooling our twins with a friend who has an old VW sedan with only a middle lap belt. To make all three kids fit in their car, we've moved one of our Radians into the middle position and the other two 5 year olds will be riding in boosters (their kid already rides in a booster full time).

In our car, my 5.25 year old twins have been riding in Radians and I planned to keep them in there until they were six or no longer fit (I am OK with them in boosters for the short ride to and from school in their friend's car). But now we are in the position that we only have 1 Radian for our car. So the question is, do we just switch them to HBBs which would be about $140 for two Turboboosters or do we spring for another Radian for $219 (we're in Canada, so that's the sale price on the Radian 65's right now).

My twins are pretty mature and usually take safety warnings very seriously, so they probably could handle the boosters, but this is earlier than I thought we would make the switch, so I'm just not sure... What would you do?

How big are your twins? How much growing room do they have in the Radians? Would you consider keeping them in harness seats beyond 6 years old?

Would you be able to get your Radian back from your friend when you are doing a longer drive?

My twins are 6y9m old and I still have them harnessed full time in our main car. DS is in a Regent and DD is in a Radian. My very large DS outgrew the Radian at 5y10m and went to a booster seat in our secondary car and in the babysitter's car. DD moved to a booster seat in our secondary car after she turned 6yo. I'm keeping my kids harnessed in our main vehicle because we have seats that still fit them and I like the support the harness provides when they sleep in the car on longer trips.

I'm not sure that I would buy another harnessed car seat for twins who are mature enough to ride in a booster seat at 5.25yo - especially if we would get less than a year of use out of the seat and I could use my other harness seat for longer twins. For my twins, I would have considered it though. We have a 25min drive to school with freeway driving. My DS wasn't mature enough to ride in a booster at that age and my DD was such a lightweight (under 40lbs at that age) that I was concerned about submarining.

Not sure if that helps you make your decision though.

Melanie

I would get a harnessed seat for a kiddo that age. I prefer it. It keeps them in place especially while sleeping, and not in charge of their own safety. A lot of folks here would booster at that age, but as I said, I prefer the harness. The kids had no problem buckling up and unbuckling, where as the booster was a problem. That's the age Hannah was when she got the Nautilus. She used it harnessed until this summer at 8.5. Now she's using it as a booster.

Even now, at 8.5 and almost 7.5, they don't stay in place that well without being reminded. They especially like to lean forward out of the headrest of the booster.