Too tall for Chicco Keyfit 30?

[Kestrel]

I'm getting concerned about how DS fits in his infant seat. He's very, very tall for his age (97 percentile). There is about 2 1/2 inches between his head and the top of the shell, BUT... his legs are so long, he can't keep his legs straight! His feet are against the vehicle seat, and his legs must be bent. Is it safe to keep him in his keyfit until his head is an inch from the top, like recomended, or do I need to move him now? He's only 19 pounds and 5 1/2 months!

We're looking at the Britax Boulevard CS (for a Ford Escape).

Please help! I'm confused!

[Joolsplus2]

It's absolutely NO safety issue if feet hang over the edge, the ONLY measure is weight and the amount of shell over the head. And that's a good thing, because my 3 and 4 year olds are perfectly happy rearfacing, even in Britaxes, which have considerably less leg room than the Key Fit (surprising but true... my dd's feet weren't at the edge of the KF when she was year, but at 5 months they were already at the edge of her Britax...). It's really ok, they just cross their legs or prop them on the seatback, it's a lot like sitting in a la-z-boy chair, and the danger to legs only comes when kids must go forward facing and their legs and feet start sustaining injuries from flying forward and hitting seatbacks :(