While I’d love to say a visual inspection is best…. it’s not. It’s not easy to know the exact condition of belts and hoses by looking at them as most fail from the inside out.
With that being said, rubber hoses can become hard and brittle. Which you can see or feel. You really don’t want to wait until this happens as they could fail at any time.
According to the Car Care Counsel, nearly one-third of all cars and light trucks have belts or hoses that should be replaced. The following link will give you more information on these.