Question 5-pt harness or high-back booster?

My 5 1/2 year old is close to outgrowing his Britax Marathon (he's 45 inches and it goes to 46--his ears are still below the top of the seat). I've read all the info and FAQ, but I can't figure out what it means when it is said that the child should be "mature enough" to sit in a booster with a seatbelt. Is this physical maturity (and if so, what are the size standards)? Or is it emotional maturity (as in, won't try to wiggle out of the shoulder belt)? We are all seatbelt fanatics in my family--my DH won't move the car unless everyone is buckled up, and my DS (age 5 1/2) freaks out if you even mistakenly put the car in gear and he's not got himself all the way buckled, so I think he meets the emotional maturity part.

[wendytthomas]

Welcome.

Are his shoulders below the top slot? If not, he's already outgrown it. The 46" (or 49", or whatever it states) really doesn't mean anything. As stated in the manual it's outgrown when the shoulders go over the top slots, when the tops of the ears go above the top of the shell, or at the weight limit.

At 5.5 if he would sit properly (and it sounds like he would), a booster is a fine option for him.

Wendy

No--his shoulders are not above the top slot.

Thank you.

[pippi2077]

He might have already outgrown the MA (like Wendy said). Our DD just turned 5y this month is 53# and 45" and she outgrew her BV last year before turning 4y. But our kids do have long torsos. She is in a 5-point, but that is because we had to replace her seat when she was not yet 4y.

DS just turned 6y and we had to replace his seat shortly after he turned 5y. He's was expiring. We moved him to a booster and he has done wonderful! He has a SK monterey and turbo. He much prefers the monterey over the turbo now. He is currently 63# and 4'1". He is on the last setting in the turbo and will outgrow it over the summer.

[jdjr6735]

I think by maturity, they're referring to boys like mine (turning 5 next week) who wiggle and move the seat belt around and stuff. I just bought him a Frontier 85 because I love having him in the harness, and he thinks it's a "big boy" seat (he didn't have cupholders in his marathon). He's VERY tall....47"....and there is PLENTY of growth room for him. So we're both happy! And he can stay immature! :P

[pippi2077]

If he hasn't outgrown the MA, I would use it until he outgrows it. How close are his shoulders to the top slots? Then I would get him a booster if you think he can sit still.

Originally Posted by pippi2077

If he hasn't outgrown the MA, I would use it until he outgrows it. How close are his shoulders to the top slots? Then I would get him a booster if you think he can sit still.

This is my plan--not to replace the Marathon until we need to. But I'm starting my research now. My son is 45" and 47 lbs. --the info on Britax's website says our seat is good to 65 lb and 49". His ears are well below the top of the car seat. His shoulders about an inch from the top slots. I think he'll do great in a booster, and if he doesn't I have no qualms about going to a 5-pt harness.

Thanks!