What Do Tire Numbers Mean?

Every time you check the inflation or wash your new or used vehicle, you see the numbers on the sidewall of the tires. The series of letters and numbers tells service technicians the size and type of tire and its specific performance and purpose. We’ll explain what these numbers mean so you’ll know the next time you need tires for your vehicle or if you’re ever curious about what the tire numbers mean. 

What Do the Numbers on Tires Mean?

When determining a tire number’s meaning, the exact code highlights the size, load index, speed rating, and type of tire your vehicle needs for optimal performance. 

Take this code for example:

P215/65R17 100H

The Letter “P” on the Tire Number Series

The “P” stands for “P-Metric tire,” because it’s used for passenger vehicles, such as cars, SUVs, crossovers, minivans, and smaller pickup trucks. If the tire numbers start with “LT,” this stands for “light truck,” and the tire works best for bigger pickup trucks. 

What Does the “215” Indicate on a Tire Number?

Following the “P” is the “215” number. This number shows the width of the tire in millimeters. The number 215 would be 215 millimeters or 21.5 centimeters. That equals about 8.5 inches or the width of a piece of paper. 

What Does the “65” Mean in This Tire Number?

After the forward slash, you see the number “65.” This showcases the ratio of the height of the tire’s cross-section compared to its width, a figure known as the aspect ratio. In our example, this tire has an aspect ratio where its height is equal to 65% of the tire’s width.

Decoding What the “R” Means on a Tire

The “R” indicates the tire’s construction, with “R” representing that it’s a radial. You might also see “B” for belt and “D” for diagonal. Inside each rubber tire are steel belts that support the rubber.

What Does the “17” Indicate on a Tire?

“17” indicates the wheel size as its diameter. By the wheel we mean the round metal part around which the rubber tire fits. This code tells us that this tire is meant for a 17-inch wheel. Car wheels may range in width from 14 to 20 inches, with some specialty wheels getting larger.

What Does “100H” Mean at the End of a Tire Number?

At the end of the code is “100H,” which highlights the load index and speed rating for the tire. The load index (“100” in this instance) indicates the weight the tire can support after it’s inflated all the way. Typical passenger vehicle tires range from 75-105 for their load index. Meanwhile, the “H” represents the speed rating, or how fast the tire can go safely. Speed ratings range from A to Z. An H tire can go up to 130 mph. 

How to Check Tire Pressure on Your Vehicle’s Tires

Regardless of what tires your car needs, they need to be inflated properly to get the best handling and improved gas mileage on every Modesto drive or Manteca weekly errand. Checking your vehicle’s tire pressure is simple. 

Most modern, high-tech vehicles have a Tire Pressure Monitoring System (TPMS). If your vehicle’s tires are over or under-inflated, you’ll see it on your TPMS. When that happens, head to the nearest gas station to put more air in the tire. You can also put air in your tires using a compressor you keep in the trunk or cargo area and even a bike pump.

Contact Us for Tire Service Near Stockton

If you need tire service, contact us or call 209-638-7997. We’ll be happy to help you with new tires, fixing a flat tire, wheel alignment, or a tire rotation. We’re happy to help in any way we can!