How to Read Tire Size

Tire Shop near Me

At some point in time, many drivers near Egg Harbor, Atlantic City and Vineland will need to replace their tires or upgrade to a new set for an improved look or performance. When you find yourself searching for new tires, it can be helpful to know how to read tire size. It can be very confusing, trying to understand what those strange letters and numbers on your tires’ sidewalls mean. Take a moment to learn exactly how to decode the symbols to find the right tires, as well as where to go if you have questions.

Reading Tire Size: Tire Width

The first number you see in the tire size lineup is a measure of the width of the tire (in millimeters) when mounted on a rim of the proper width. One of the following letters will come before the first number:

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

You’ll want to choose a letter based on the type of vehicle you’re equipping with tires. Light trucks usually require higher inflation pressures than passenger tires. If you’re unsure what width or type of tire to pick, or how much to inflate your tires, you can always check your vehicle owner’s manual to confirm.

Aspect Ratio

The number immediately after the forward slash (/) will be the aspect ratio. This is the ratio of the height of the tire’s cross section to its width (in terms of percentage). For example, if the number there is 40, you know the tire’s height equals 40 percent of its width.

Speedy Tires? You May See a “Z”

If your tires are built for the highest-rated speed, you’ll see the letter Z appear next in the lineup. For all other tires, this designation will be found in another place on the sidewall, so you can discount it when trying to read tire size.


The next letter indicates tire construction. It will either be an R (for radial-ply tires, meaning the layers of cords run radially across the tire) or a D (for diagonal-ply tires, now used exclusively on trucks and trailers).

Wheel Diameter

The number immediately after the construction letter (R or D) refers to the diameter of the wheel. So, if the tire size code reads P215/65R17, you can expect that tire to fit wheels with a 17-inch diameter.

Schedule Service at Our Tire Center

Now that you know how to read tire size, the Boardwalk Acura tire center is here to help when you need a new set. We stock tires designed for optimum performance, comfort and safety, and we’ll ensure you get the right ones for your vehicle. When it comes to tires, we do it all at your dealership serving Vineland, Atlantic City and Egg Harbor. If you have your tire size number, you can enter it in our online tire search tool to see if we have the right size in stock. Then, just place your order and schedule a visit, and our team will mount your tires on your wheels. Get in touch with us to get started today.