for those with big babies...

[AnnieW625]

If I buy a convertible car seat now that goes up to 65lbs, why wont it last my son until he's ready for a booster seat?

He will most likely outgrow it by height not weight, but yes most 40, 50, and 65lb convertables last until a child is ready for a belted high back booster (Britax Parkway, Sunshine Kids Monterey, or Graco Turbo Booster) or if you choose to keep him harnessed longer then there are other choices like the Graco Nautilus, Britax Frontier, and the newly introduced Evenflo Generations 65 which al convert to high back boosters to be used with a belt. It seems the standard age for that in many places is 4 or 5 years old. Or get something like a Sunshine Kids Radian or a Britax Regent that will harness up to 80lbs, but don't become high back boosters. And FWIW there are lots of parents who post here and other carseat forums like Car-seat.org that keep their kids harnessed way past the norms in most areas where we will live. It's not unusual to see pics of kids on car-seat.org being harnessed at 7, and 8 years old.

As an example when Elisa outgrew her Evenflo Triumph 5 (a small 40lb seat that is no longer sold) by height we got her a Britax Frontier so we can keep her harnessed for a longer period of time because she is only 3 years old, we'll probably move her to a high back booster at around 5 or 6 depending on how she acts in the car and such.

Hope that helps out some!