How to Read Tire Size

Drivers near Albuquerque, Rio Rancho and South Valley know all about how important rotating your tires is to their long-term reliability. But what happens when you need to replace your tires? If you’re searching for a new set, it may be helpful to know how to read tire size.

And that’s exactly what our team at Jaguar Albuquerque is here to help you do. The size code on your tire sidewalls is actually very easy to read when you know what all the numbers and letters mean. We’ll walk you through everything you need to know!

Tire Width

When you locate the tire size code on your tire sidewalls, the first number in the sequence is the width of your tires, measured in millimeters. It will be prefaced by one of the following letters:

  • P = Passenger Car
  • T = Temporary Spare
  • LT = Light Truck
  • ST = Trailer

Most drivers will want to look for the letter P, but if you happen to drive a truck or are looking for tires to fit your trailer, you’ll want something different. The tire width number will come right after the letter code to identify vehicle type, and it will have a forward slash (/) separating it from the next number.

Aspect Ratio

The number right after the forward slash (/) represents the aspect ratio, a measure of the ratio of a tire’s cross-sectional height versus its width. It’s expressed as a percent, so the number 70 would indicate that the tire’s height is 70 percent of its width. The aspect ratio determines the height of the tire’s sidewall and affects steering stability.

Tire Construction

The aspect ratio will be followed by another letter to designate tire construction. This indicates the design of the cords that make up the tire. The symbol you’re looking for is most likely R, the standard design for automotive tires. It refers to a radial-ply design, in which the layers of cords run radially across the tire.

However, if you need tires for a truck or trailer, you may want to look for a D (for a diagonal- or bias-ply).

(Note: you may see a Z before the tire construction—as in 215/45ZR18—if your tires are highly-rated for speed.)

Wheel Diameter

The final number in the sequence refers to the wheel diameter, measured in inches. If your tire-size code reads P185/55R15, you can gather that the tire is made to fit wheels with 15-inch diameters.

Jaguar Albuquerque

When you’re wondering how to read tire size, just refer to this article for all you need to know. And if you need to order new tires and want help fitting them to your vehicle, don’t hesitate to contact the tire shop at Jaguar Albuquerque.

Our technicians can help you choose the ideal tires to boost your vehicle’s safety, looks and performance. And, they’ll ensure those tires are mounted correctly, so they do their job optimally and get you anywhere you need to go in Albuquerque, Rio Rancho or South Valley. Schedule your service online today!