What symptoms are you trying to correct?
A strut is a shock absorber ( damper ) that is a structural component of the
suspension. Failed dampers will leak and/or let the car/wheel oscillate over
bumps. The test here is somewhat subjective, my test is to kneel on the
bumper and release. The car should go up then a slight movement down then
If it goes up, down then up again the dampers are worn.
If you are trying to correct for a sag, the springs are the source of the
problem if the tires are the same model and size. Tires from different models
with the same size on the sidewall sometimes differ in actual height.
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