What does 215/55r17 on a tire mean?
2 Answers
Tire 215/55r17 refers to: 215 indicates the tire section width in millimeters; 55 is the aspect ratio, representing the percentage ratio of the tire sidewall height to the tire section width (55 means 55%); r stands for radial, indicating the tire has a radial structure; 17 is the rim diameter in inches. The tire sidewall is marked with an arrow or the word OUTERSIDE, indicating the tire's rotation direction. A small umbrella symbol on the sidewall means the tire is suitable for driving in rainy or slippery conditions. Some tires may also have other letters or symbols with special meanings, such as "X" for high-pressure tires, "C" for reinforced tires, "B" for bias-ply tires, and "-" for low-pressure tires.
I've been driving for over a decade, and reading tire specifications is like recognizing an old friend's face. The number 215 in 215/55R17 refers to the tire width in millimeters, which is essentially the size of your tire's contact patch with the road. The 55 is a percentage, professionally known as the aspect ratio, meaning the sidewall height is 55% of the width—the smaller this number, the flatter the tire. The R stands for radial construction, which over 90% of vehicles use today. The final 17 indicates a 17-inch wheel diameter. This specification is quite common, used by midsize sedans like the Accord and Camry. A 215 width offers moderate grip, while a 55 aspect ratio balances comfort and handling. Always remember these numbers when changing tires—wrong wheel size means they won't fit, and altering the aspect ratio completely changes the driving feel.
