You'll find the optimal or manufacturer-recommended tire pressure for your car on the door frame sticker or your car's owner's manual. Some car models even have stickers on the trunk lid, dashboard or on the gas door. Recommended pressure is usually between 30 and 35 PSI. This number indicates the minimum amount of air pressure required to support the vehicle's maximum load-carrying capacity. Anything less and you'll experience poor fuel economy and handling, as well as premature tire wear from too much flex and tire overload. When your tires are inflated to the recommended PSI level, they will perform optimally.