Should have recommended PSI range on side of your tires. Sometimes hard to see but you'll find it. Every brand and model have different recommendations. Or maybe you can look up your tires online but by the time you find Make/model and size on your tires you'll probably find the pressure range. You can find the right pressure charts and graphs online for you weight + bike to tell you their suggestions. But I just run highest tire range for hard roads and toward lowest for gravel. But I'm just that way.