Max height for LBB?

[mommybug]

I picked up an Affix LBB for DS1 and just saw that it has a max height of 57". Why is there a max height for a LBB? Is it a firm height limit? DS1 is about 56" now so I'm not going to get much use out of it if I can only use it for another inch.

On a another note, I thought that I read somewhere that around 59" is about the height that kids start passing the 5-step test but I can't figure out where I read that. Did I just make up that number in my head?

Thanks!

[Joolsplus2]

I'm lax about top height limits, as long as the belt still fits right and the head has whiplash protection (ie, headrest at least up to the tops of the ears), it's more of a guideline. 57" (4 foot 9) is the 'magic number', per the NHTSA ads. https://www.youtube.com/watch?v=o8KK5vrcMyY
For some cars, that's a good height, like in the third row of my Mazda5, DD2 should be fine then, but in other cars the seat is so deep that kids' butts scootch forward almost immediately so their legs can bend, and the lapbelt rides right up onto the abdomen...a big ol' captain's chair might require a booster till 5 feet or so. And even in some cars the 'five step test' doesn't work so well, I find the lapbelt riding right up all the time on ME, so my rule is 'butt all the way back, feet flat on the floor'--no specific age/height/weight, and it's easy for kids to test themselves.
Gratuitous blog with my now-15 year old...http://carseatblog.com/3966/the-5-step-test/