Your tire size is located on the side of your tires. The three digit number is the millimeter size of the midsection’s width. The next two digit number is the height/ width ratio. The last number is your size. Usually in the range of 15-20. Obviously there a specialized tires so that could vary. The first letters in the number string refer to the type of tire for like passengers (p) and other things of that nature. The Last letter refer to the type of tire construction (like radial or belt biased tires). If you just want to know the size focus on the last set of two digit numbers.