Why 4 And 40?

Melizerd · Jan 4, 2008

Is there a specific scientific reason for 4 and 40 for a booster? This question was asked elsewhere and I realized I just go by it and never really thought about WHY.

I mean there are some obvious reasons like maturity and size but is there something more concrete?

natysr · Jan 4, 2008

Okay, you know I'm not a tech, but I'm going to go out on a limb here.

My answer is that it is an arbitrary bare minimums of when a child *should* be safe in a booster. Just like 1 year and 20 pounds is an arbitrary bare minimum when a child *should* be safe forwardfacing.

Perhaps there is statistically a significant decline in child injuries in boosters after 4 and 40? I'm sure that is what you are looking for though.

joolsplus3 · Jan 4, 2008

Because that's what most convertibles have historically gone to (just like 1 and 20 was based on seats only RF to 20... ). And that's why most of us don't say 4 or 40 anymore...because there are SO many HWH options (yay!)...I just say 5-6 and now weight now, as that's when head injury risk from being in a booster drops to a lower level. (people are still boostering at 3 and 30 because boosters start at that age, so saying 4 and 40 is still aiming high for most of the population

)

Melizerd · Jan 4, 2008

Yeah that's what I'm wondering too. I mean I realize we need SOMETHING as a minimum I was just wondering if there is something specific with data.

You know me, once I start thinking about something I gotta know everything I can (lol).

joolsplus3 · Jan 4, 2008

It's just arbitrary

(And has nothing to do with the sizes of crash test dummies...well, the 20 pound one was a sandbag with a head...but there's no 40 pound dummy... THAT leaves me wondering a little!)

Melizerd · Jan 4, 2008

ok well at least I know WHY even if it's not a good reason (lol). Whomever though a sandbag would be similar to a child should be shot though

skaterbabs · Jan 4, 2008

dummies have gotten a lot better, but the first car seats weren't designed so much to reduce injury as to just keep the kids stationary in the car. A weighted flour sack would indicate whether or not the seat would hold the given weight, even without any injury data.

melniemi · Jan 4, 2008

joolsplus3 said:
It's just arbitrary

(And has nothing to do with the sizes of crash test dummies...well, the 20 pound one was a sandbag with a head...but there's no 40 pound dummy... THAT leaves me wondering a little!)

Then how do seats get a 40 pound maximum weight?????

joolsplus3 · Jan 4, 2008

Mathematical extrapolation... they say, well, a 33 pound dummy moves forward x inches, a 40 lb dummy will move forward y inches... (that's about as much as I know...I wonder if we can get our hands on the real formula....). Canada has a few seats that go to 48 pounds...that makes sense! That's what the 6 yo dummy weighs...

melniemi · Jan 4, 2008

I'm not sure I'd want to trust a mathematical equation with my child's life? Why wouldn't all companies just use the 48# dummy and create their seats to hold that weight? It makes more sense than 40#s off an equation and then my 6 yo would still fit in his Cargo!

amy919 · Jan 4, 2008

I've wondered this myself many times. I have a 5 year old who is very mature and would sit correctly in a booster every time for the short trips she'd be in it. She's in a Regent in my car, but until this new Graco Nautilus surfaced, I was really stumped on what to do for her. She's only 35 pounds, so I'm not willing to put her in a booster. Matt has continously argued with me about just getting a Parkway or a Monarch since they specify 30 pounds and up. I couldn't really come up with any good factual evidence on WHY she couldn't be a in booster, except because I said so, which is more than enough.

I did win the battle, though when the Regent showed up and I put my 25 pounder in it and showed Matt that she "fit" according to the specs on the box. He stopped bugging me about the booster after he saw our peanut in the throne

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Why 4 And 40?

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