It is extremely important to use tether anchors when you're carseat is forward facing. Did you know that if your car doesn't have tether anchors, you can often have them retrofitted? If you don't know how to go about doing this, read you car's manual. It is very important that you know where the anchors should be, here's my story.....
My mother drives a 1999 Ford Escort Wagon. Sofi is currently rear facing in her car, but one day she will be forward facing. We decided to have the tether anchors installed, so we're ready when that forward facing day comes. I call the Ford dealership of my mother's choice. The dealership ordered the anchors, and called her once they came in, and set up an appointment. My mother had them installed, and I took a look after it was done. According to the 2009 LATCH Manual, the tether anchors should go in the ceiling. Where did Ford install them? On the floor. How odd. I checked the car's owner's manual, and spoke with some CPSTs online, and we decided that they were installed incorrectly. I spoke with the dealership twice, and will soon be going to have them reinstalled. I will be going with my mother this time, to make sure they are placed correctly.
