What is the difference between a 22570 tire and a 21575 tire?

The difference between a 225/70 tire and a 215/75 tire lies in their width and aspect ratio. The first number represents the tire width in millimeters, so a 225 tire is wider than a 215 tire. The second number indicates the aspect ratio, which is the height of the sidewall as a percentage of the width; a 70 aspect ratio means the sidewall height is 70% of the width for the 225 tire, while a 75 aspect ratio means the height is 75% of the width for the 215 tire. This results in the 215/75 tire having a taller sidewall compared to the 225/70 tire.