It depends on the type of bike and tire you’re running. All bike tires will have a recommended psi range listed on their sidewalls, so try to stay within that range. For most road riders, pumping tires to between 70 and 90 psi is a good starting point, while mountain bikers will run anywhere from 18 to 35 psi depending on the rider’s weight and the terrain. It is often a process of trial and error to find the optimal pressure for your tires, riding style, terrain, or road conditions to get the best performance from them.