Given that struts are structural, they're naturally made to last a long time. On top of that, be able to take a beating during your day-to-day commutes. It has to absorb a lot of vibrations, bumps, and knocks. Their robustness means that struts could easily last in excess of 100,000 miles before they require a replacement. Nevertheless, it's a good idea to have your struts checked out after 40,000 miles or so. A brief inspection should be more than enough. The precise interval will vary depending on how much strain you put on your car. For example, higher performance or heavy-duty cars will likely wear out their struts much sooner.