Federal law requires tire manufacturers to place standardized information on the sidewall of all tires. This information identifies and describes the fundamental characteristics of the tire and also provides a tire identification number for safety standard certification and in case of a recall. The tire size is listed on the side wall where the red arrow is. Keep in mind that trailer tires are “ST” tires (Special Tire) therefore your tire size will start with ST. An example of a tire size would be ST205/75R14.