Regularly inspecting tires is very important to avoid a flat and detect problems with steering, or suspension. When the tread depth is not good, it will be sensed and replacement should be done. For example, the wheels are not aligned properly if you see cupping. If necessary the valve core should be tightened while punctures are repaired. Brake fluid leaks can be found on the inboard side of each tire by inspection. Tire pressure is a major determinant of tire life span, mileage, and quality of ride and it should be checked up by a reliable gauge that shows the correct reading. On a cold day, compare this to what is indicated on the tire placard on your left door jamb (tire sidewall).