How tight should the car seat installation be?

The car seat should not move at the belt path more than 1 inch (2.5 cm) from side to side or front to back. To test for tightness, grab the sides of the seat where the lower anchor strap or vehicle seat belt is routed and slide the car seat side-to-side and front-to-back. If the seat moves less than 1 inch, it is tight enough.