This is a common question. There are many variables and there is no set number on how many miles you should get out of a shock absorber. What brand of shocks do you have? This is the most important factor on how long they will last. Entry level shocks or the originals from the factory will not last nearly as long as a high end, more expensive shock like Bilstein. If you had to put a number on it, many professionals recommend changing out your factory shocks around 50,000 miles. This number can vary greatly with variables like the kind of driving you do and the condition of the roads in your town.