How to read a tire size?

You can find the information about your tire on the sidewall of your tire. They are known as tire markings and they provide load capacity, model, construction type and tire size. The first two letters represent what the tires are designed for. Example "M + S" means the tire is made for mud and snow. The next letter stands for vehicle type. Example: P stands for passenger vehicle. The next section is a three digit number which tells the width across to the outside opposite wall. Example: 185 means it is 185 mm across. The following number after the slash mark is the aspect ratio of height to width. Height is the area from the inner tire to the top of the tread. Example: 80 means the the tire's height is 80% of the width. The next letter represents the type of tire. Example: R means it is a radial tire. The last number represents the rim size. Example: 18 means that the rim has a diameter of 18 inches. You can always ask a salesperson for help but it is good to know what you need.