How to Read Tire Size

How to Read Tire Size

From providing a balanced support to your car to helping you cross new roads, your vehicle’s tires play many important roles. Your tires will wear over time, and in preparing for your next set, it may be a good idea to understand how to read your tire size.

For drivers near Rockwall, Mesquite, and Garland, Texas, curious about reading the correct tire size for their vehicle, the Rockwall Ford team put together this quick guide. Read on to learn more!

Understanding Your Tires

Anything you need to know about your tire size can be found on the sidewall. However, this series of numbers can be a bit confusing to understand, as each is important to the overall tire fit. Below, you can learn what each number and letter, in order, on your tire’s sidewall means:

Tire Type

The first letter on the tire indicates the tire class, which is typically marked by P, LT, or ST:

  • P: Passenger vehicle tire (for cars, SUVs, crossovers, minivans, and small pickup trucks)
  • LT: Light truck tire (for heavy duty vehicles that can have a high towing capacity)
  • ST: Special trailer (for trailers)

Tire Width

The next three-digit number is the tire width in millimeters. This measures the tire width from sidewall to sidewall.

Understanding Your TiresAspect Ratio

The aspect ratio is the number that comes after the slash on the tire. This is a measure of the tire’s height represented as a percentage of the tire’s width. If, for example, the number is 65, the height is equal to 65% of the tire’s width.

Construction Type

Next, your tire will list the construction type with a single letter:

  • R: This is a radial tire, which is the industry standard for most tires today.
  • D: The tire is built with diagonal plies and can be called conventional, x-ply, or cross-ply tires.

These are the most common tire construction types that you will likely see. If you see a different marking, you can always reach out to our team to learn more about your tire’s internal construction.

Understanding Your TiresWheel Diameter

The 2-digit number following the construction type is the wheel diameter, which is measured in inches. This measurement indicates the size of the wheel that the tire is intended to fit.  

Load Index

The load index is a number that corresponds with the maximum weight a tire can support when properly inflated. You can use the load index to determine the maximum weight in pounds.

Speed Rating

The final letter on your tire’s sidewall is the speed rating, which can tell you the top safe speed capability of your car. You can find the corresponding speed depending on the marked letter. For example, an H speed rating means your vehicle’s maximum speed capability is 130 MPH.

Find the Right Tires at Our Service Center!

When it comes time for Rockwall, Mesquite, and Garland, TX, drivers to find the right tires for their vehicle, it’s good to understand how to read tire size. When you visit our Rockwall Ford service center, our team of technicians can help you find and install the right tires.

Contact our team today!

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