What Does Each Number on Tire Size Mean?
Have you ever looked at the side of your car’s tire and wondered what all those numbers and letters mean? It may look like a secret code, but understanding tire size is simpler than you might think.
In just a few minutes, you’ll be able to decipher those mysterious markings and make informed decisions when it’s time to replace your tires.
Tire Type
The first letter in the sequence, “P” in our example, stands for the tire type. “P” means it’s a passenger vehicle tire, designed for cars, minivans, SUVs, and light trucks.
If you see “LT” instead, that means it’s a light truck tire, made for heavier loads and more rugged use.
Tire Width
The first three-digit number after the tire type letter represents the tire width in millimeters. In our example, “215” means the tire is 215 millimeters wide from sidewall to sidewall when mounted and measured on the specified wheel rim.
Aspect Ratio
Following the tire width, you’ll see a slash and then a two-digit number. This is the aspect ratio, which is the height of the tire sidewall expressed as a percentage of the tire’s width. In our example, “65” means the sidewall height is 65% of the tire’s width.
Construction Type
The next letter in the sequence tells you the tire’s internal construction. “R” means it’s a radial tire, which is the most common type on modern vehicles.
Radial tires have reinforcing plies that run perpendicular to the direction of travel, offering a smooth ride and good fuel efficiency.
Wheel Diameter
After the construction type, you’ll see another two-digit number. This represents the wheel diameter in inches, which is the size of the wheel that the tire is designed to fit. In our example, “15” means the tire is made for a 15-inch wheel.
Load Index
The next two digits after the wheel diameter represent the load index, a code that corresponds to the maximum weight the tire can support when properly inflated. In our example, “95” means the tire can support up to 1,521 pounds.
Speed Rating
The final letter in the sequence is the speed rating, which indicates the maximum speed at which the tire can safely operate. In our example, “H” means the tire has a maximum speed of 130 mph.
It’s important to note that speed ratings are based on laboratory tests and don’t reflect real-world driving conditions or legal speed limits.
Conclusion
Now that you know what each number and letter on your tire’s sidewall means, you’re better equipped to make informed decisions when it’s time for new tires.
Keep in mind that choosing the right tire size is crucial for your vehicle’s safety, performance, and fuel efficiency. When in doubt, consult your owner’s manual or a trusted tire professional to ensure you’re getting the best fit for your car and driving needs.
So the next time you’re admiring your car’s sleek wheels and tires, remember that those numbers and letters aren’t just for show—they’re a vital code that unlocks the secrets of your tire’s capabilities.
With this knowledge, you can hit the road with confidence, knowing that you’ve got the right tires to get you where you need to go.
Meet Caitlin McCormack, a Tire Size Expert and Blogger Passionate About Everything Related to Tires. With Years of Experience in the Tire Industry, Caitlin Has Become an Expert in Tire Sizes and Their Impact on Vehicle Performance.