What Do All Those Numbers on Your Tires Mean?

close up of numbers and letters on the sidewall of a tire

If you’ve ever looked closely at your car’s tires, you’ve probably noticed a string of numbers and letters on the sidewall. While they may seem confusing (or even a bit overwhelming), these numbers provide crucial information about your tires, such as their size, performance capabilities, and safety ratings.

In addition to helping you find the right size for your vehicle, these numbers help you choose the best set for your driving preferences, climate, and performance needs. This article covers everything you need to know to help you make the most informed decision the next time your car needs new tires.

1. Tire Type

The first letter in the tire code indicates the type of tire. Most commonly, you’ll see:

  • P: Passenger vehicle tire, which is the most common tire type for cars, SUVs, and light trucks.
  • LT: Light truck tire, designed for vehicles carrying heavier loads or tow trailers.
  • T: Temporary tire, commonly known as a spare tire.

For example, if your tire reads “P215/65R16,” the “P” means it’s for a passenger vehicle.

2. Tire Width

The next number after the tire type is the width, measured in millimeters from sidewall to sidewall. For example, in the code 215/65R16, 215 represents a tire width of 215 millimeters. A wider tire often provides better traction, while a narrower tire can improve fuel efficiency.

If you regularly drive in snowy or rainy conditions, narrower tires can provide better traction, leading to safer driving and easier handling on wet roads.

3. Aspect Ratio

Aspect ratio isn’t just a TV or photo setting – it also refers to the height of the tire’s sidewall as a percentage of its width. For example, in the code 215/65R16, the number 65 means the tire’s height is 65% of the tire’s width. A lower aspect ratio (like 50 or below) often indicates a sportier tire with a shorter sidewall, which can improve handling but may result in a firmer ride.

For most daily driver vehicles, an aspect ratio between 55 and 70 will provide the right balance of comfort and performance.

4. Tire Construction

The letter R in the tire code stands for Radial construction, the standard in most modern tires. Radial tires have layers of fabric that run at 90-degree angles to the direction of travel, providing better control, durability, and fuel efficiency.

Today, nearly all passenger and light truck tires use radial construction as it provides the best combination of durability, fuel efficiency, comfort, and handling capabilities.

5. Wheel Diameter

The number following the letter “R” indicates the diameter of the wheel (or rim) that the tire fits, measured in inches. In the example 215/65R16, the number 16 tells you the tire fits a 16-inch diameter wheel.

Ensuring the tire matches the correct wheel size is critical for proper fit and performance. If you have any questions about sizing, the expert and certified technicians at your local Dobbs Tire and Auto Centers location can help you pick the proper set for your vehicle.

6. Load Index

If you use your vehicle for work or regularly transport heavy materials, it’s essential to consider the load index when purchasing new tires. The load index is the maximum weight a tire can support when fully inflated.

Typically, you’ll see this number listed after the tire size, such as in 215/65R16 98H. In this case, the number 98 refers to the tire’s load-carrying capacity. Each number corresponds to a specific weight rating, but it’s not as intuitive as some other numbers (for example, 98 means the tire can hold 1,653 pounds). If you need additional guidance, review your vehicle’s manual to ensure the load index meets or exceeds the requirements for your car.

7. Speed Rating

The speed rating is represented by a letter and indicates the maximum speed the tire can safely handle when properly inflated. In 215/65R16 98H, the letter H stands for a speed rating of up to 130 mph. Standard speed ratings include:

  • S: Up to 112 mph
  • T: Up to 118 mph
  • H: Up to 130 mph
  • V: Up to 149 mph
  • Z: Over 149 mph (high-performance tires)

Make sure the speed rating is appropriate for your vehicle and driving conditions, but remember, just because your tires can handle high speeds does not mean you should push them to the limit!

Tire Identification Number (TIN)

Separate from the tire size, the Tire Identification Number (TIN) is a series of letters and numbers that provide information about where and when the tire was manufactured. The TIN can help track recalls or reveal the tire’s age. It’s important to note that aging tires can become unsafe after a certain period.

Find the Perfect Fit at Dobbs Tire and Auto Centers

From enhancing safety to increasing your vehicle’s handling capabilities, the right tires can significantly improve your overall driving experience. But with so many options, determining the best set for your vehicle can be challenging.

Make an appointment at a Dobbs Tire and Auto Centers location near you and let our expert and certified technicians help you find the correct set at the most affordable price.