What Do Tire Numbers Mean?

If you’ve ever looked at the sides of your tires, you probably noticed several numbers imprinted on them. What do these tire numbers mean? It’s important to know how to read those tire numbers so you can properly inflate your tires and know which size to choose when replacing them.  The service team at Mercedes-Benz of Tysons Corner likes to keep our customers informed so that they can keep their vehicles running in top shape. After all, no one wants to find themselves stranded somewhere in the Chantilly area with a flat tire. So, let’s answer the question, “What do the numbers on tires mean?” together!

What Do the Numbers on Tires Mean?

Tire number meaning can be broken down into two main categories: size and air pressure. Each category is identified by the letters that accompany them. So, the next time you’re wondering, “What does this tire number mean?”, check how it’s formatted.

Tire Number Meaning: Size

Numbers that indicate size are usually formatted in one of these two ways: “P225/50R16” or “225/50R16”. Here’s what those numbers on your tires mean:

• Letter at beginning
  • P – Passenger vehicle
  • T – Temporary spare
  • LT – Light truck
  • ST – Special trailer service
• Number before the “/” – This is the section width of the tire in millimeters.
• Number right after the “/” – This is the sidewall aspect ratio (sidewall height from rim to tread)
• Letter after the sidewall aspect ratio – indicates internal construction of the tire
  • R – Radial
  • D – Diagonal or bias ply
  • B – Belted
• Number after the internal construction letter – rim size in inches

Tire Number Meaning: PSI

What do tire numbers mean when they’re followed by “PSI”? This is probably the most important number for the average Great Falls driver to know, since your tire technician will read the size numbers on your tires when replacing them). “PSI” stands for “Pounds per Square Inch” and refers to air pressure. You will need to know this number when inflating your tire, and you can find it in your owner’s manual if you’re not sure of what it should be.

Our Service Department in Vienna is Here to Help

The friendly service managers at our tire center will be glad to assist you with any of your tire needs, which includes making sure you get exactly the right tires for your vehicle. You can even schedule service appointments online. We’re easy to reach from Mclean or Bethesda, so don’t wait to reach out!