How can you tell if you need new shocks or struts?

Answer 1

Park the car and look at it from a distance directly in front and directly behind. If the front left corner is higher or lower than the front right corner, or if the back left corner is higher or lower than the back right corner, it may be time for a new suspension.

Remember to take uneven loads out of the car first (no heavy boxes in the passenger seat), and remember that most roads slope slightly toward the curb, so a difference of an inch or two is probably ok.

Other ways: If, when you drive over a bad road or railroad tracks or other rough terrain, the car should not "bottom out" (you'll feel it) on its suspension if the car is not excessively loaded.

Also, a bad suspension may cause the tires to move out of alignment, and they might start developing unusual tread wear patterns (all wear on the inside half or outside half of the tire, for example), and you'll be able to see it. There are other things that can cause this so this does not automatically point to the suspension.