I am currently working on placement for seats in our cars... my younger daughter rarely rides in my husband's car, but I want to have a spare seat for his car, just incase. (Side note-- car does not have rear airbags.) Since it won't be used often, I don't want to spend a ton, but I still want to feel that she's safe when she IS in there. I know only a few seats allow you to tether rear-facing, and they're usually the more expensive seats. I am wondering if something cheaper with good side wings is just as, or almost as, effective as rear tethering? She is 21 months and will be rear-facing for a long time, hopefully, and I know that adds safety in and of itself. Beyond that, just wondering how much safer rear-facing with a tether is. Thanks for any input!