Ok, my son weights 39 pounds and he is 40 inches tall, i hope that will help....thanks everyone
Well Torso height is more important that overall height because once the tops of the shoulders go past the top harness slots the seat is outgrown by height. Here is a list, and it also lists the highest harness position so you can make a judgement on what seats might last your ds long enough
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United States)
Convertible Seats
Britax Marathon, Decathalon, or Boulevard (MA/DC/BV). 17 in top slots, RF 5-33lbs, FF up to 65lbs in 5 point harness. Awesome seats, allow for rf tethering, has lockoffs to replace locking clips, very easy installs, many bells and whistles that make them easier to use correctly every time, lasts most kids to age 5-6y/o. 220+
Check this FAQ thread HERE for a description of the three.
Fisher Price Safe Voyage Deluxe (FPSVD).17 inch top slots, RF 5-33lbs, FF up to 55lbs in a 5 point harness. Made by Britax, sold under the FP name- basically a stripped down Britax Marathon. Great seat, awesome price $129 (regular 199$), and will last most kids to age 5-6 y/o.
DISCONTINUED DUE TO POOR SALES-- As of right now Britax is still manufacturing them but check with the store to see what the date of mfgr is that they are shipping. You may only be able to find these online.
New Evenflo Triumph Advanced RF to 35lbs; FF to 50 lbs. Max harness height of 17". The new Triumph has the infinite harness adjuster too.. no rethreading the harness! Much nicer than the old Triumph! Much taller shell than the old Triumph too! Priced at $130-150. VERY new seat so not in many stores yet I dont think. We think it will be small enough for newborns!
Sunshine Kids Radian. 18 in top slots, RF 5-33lbs, FF up to 65lbs in 5 point harness. Great seat, only second to Britax because it has some compatibility issues in some vehicles when installed with seatbelt. Really good seat otherwise, allows for RF tethering, lasts most kids to 6-7y/o. 8yr lifespan (most have a 6yr) $175+
www.skjp.com has the manual available for viewing.
Forward facing only seats (child must be over age 1, and 22#s)
Safegaurd GO. Harnesses to 60#s, becomes a no back booster after. Top slots are 17 to 17.5 inches, needs adjustable headrest behind it for support. Requires top tether anchor. Child must be 30#s to use. Retails for $179
Britax Regent (used to be Husky). KING of car seats is right! Harnesses to 80#s. Top slots are 20 inches.
Requires a top tether after child is 50#s. Retails for $220-$260. Not good for children under 2yo.
Requires college degree to read the manual.
Ride Safer Vest. A vest that comes in two sizes, Small 35-60#s, Large 50-80#s. The vest can be used with lap only belt. Requires top tether anchor & headrest. Retails for $89-$99. Great for 3 across situations in small vehicles! Tether strap HAS to be used if child is under 6 yrs old.
http://www.safetrafficsystem.com/
FF/Harness Combo Harness/Booster Seats
this is the only combo seat that goes past 40lbs
Cosco/Safety 1st Apex. Only higher weight Combo (FF harness/Booster) seat that harnesses to 65#s. Top slots are 17-1/2 inches high.
Requires adjustable headrest or a very tall vehicle seatback behind it for support. Then becomes a very nice BUT VERY WIDE booster that doesnt fit small children well.. This seat is outgrown totally when the tips of the childs ears reach the top of the vehicle seatback. (Fully extended it has a back height of 32.5in tall) The new blue/black and all the brown ones have EPP Foam in the headrest. Retails for $89-150.
(the one linked above is $90 and has EPP foam in the HR).
The Regent is the longest lasting seat because it has the tallest top harness slots. I'm actually considering one for my ds fairly soon since he's outgrowing his current seats-Britax Blvd and 2nd seat Evenflo Bolero, by height but he's not yet 40lbs - or mature enough to stay seated properly in a booster yet. The Radian comes in a close 2nd because the top slots are only 18" but according to the mfgr this is one seat that allows the tops of the shoulder to go past the top harness slots as long as the ears are stillunder the top of the shell. Still not sure how I feel about that though since in other seats the shoulders going past the top slots can cause spinal compression in an accident and I'm not sure how Sunshine Kids could have tested for that. According to them it has something to do with the frame being made out of steel though.
hth!