View Here : Tire Chart Size
For example, our tire size of 245/75-16 with a diameter of 30.47” would place it smack between equivalent off-road tire sizes of 30” and 31”. If you were not changing your vehicle's ride height and clearance in the wheel well was already tight, we'd recommend playing it safe and choosing the smaller 30" size.
For example a tire size of P225/60, the number 60 is the tire's aspect ratio. The aspect ratio represents the percentage of width to height. Therefore the height of this tire is 60% of its width.