Dear Car Talk: Can you tell me why tire sizes are designated as they are? If I understand correctly, we have metric, English and a ratio. Like, a "235-75R15" tire is 235 millimeters wide ...

When you look for new tires, you'll come across size names such as 235/75R15 or P215/65R15. These labels can be confusing if you're not sure how to read them, but once you learn the language of ...