How to Read Tire Size

Eventually, drivers across Ocala, Starke, and Gainesville will need to replace their tires. A new set of tires can really boost your performance, but choosing the right ones is essential.

Wondering how to read tire size? Our team at Ford of Ocala is here to explain what all those numbers and letters on your tires mean. Deciphering the code is easier than it looks. Once you know how to do so, you can shop tires with confidence!

Reading Tire Size: Getting Started

Reading Tire SizeThe first step in reading tire size is finding the code. You can find it stamped into your tires’ sidewalls. At first glance, it’s just a sequence of letters and numbers, but they all contain information that helps identify the tire.

The first marking should be a letter or pair of letters. They identify the type of tire, and the most common combinations include:

  • P = Passenger Car
  • LT = Light Truck
  • ST = Trailer

Choose the tires that match the body style of your vehicle. (If you’re unsure, just check the vehicle owner’s manual for confirmation.) Keep in mind, too, that different types of vehicles have difference inflation pressure requirements. They’re usually higher for trucks than for passenger cars, for example.  

Width & Aspect Ratio

The number immediately following the initial letters is the measure of the tire’s width in millimeters. Next, you’ll see a slash (/), followed by another set of numbers. This is the tire’s aspect ratio.

What exactly is an aspect ratio? It’s the ratio of the height of a tire’s cross section to its width, measured as a percentage. So, if the number you see is 65, the tire’s height is 65 percent of its width. Easy enough!

Performance Tires? Look for a “Z”

Reading Tire SizeIf your tires are designed for the highest-rated speed, the letter Z will be next up in the lineup. For all other tires, this signifier will be found on another part of your tire’s sidewall. You won’t need to worry about it as you’re reading tire size.

Tire Construction

Next up, you’ll see another letter. It tells you how the tire is constructed. This letter will be either an R or a D. “R” stands for radial-ply tires, with cord-layers that run radially across the tire. “D” signifies diagonal-ply tires, which are used on trucks and trailers.

Wheel Diameter

Wheel Diameter After that R or D, you’ll see the final figure in the sequence. This is a measure of wheel diameter, expressed in inches. Typically, this number will fall somewhere in the 15–20 range.

Shop Tires at Our Tire Center

Now that you know how to read tire size, you know everything you need to shop tires! In fact, you can do so right here at our on-site tire center. We have a vast selection of tires in store, including popular name-brands like Michelin, Goodyear, and Continental Tire.

See a glowing tire wear indicator while driving around Ocala, Starke, or Gainesville? Notice your tire tread wearing out? It may be time for a new set. Just contact the experts at the Ford of Ocala Tire Center and find the perfect tires for your ride!