Just as wearing the right-sized shoes is crucial for walking comfortably, ensuring your vehicle has the correct tire size is essential for optimal performance. So how do you know what tire size is right for your vehicle? You can refer to the owner's manual or look inside the front, driver's door jamb for information. The problem is that tire size is shown through a code of numbers and letters like P215/65R15 95H. Fear not! We’re here to help you decode these tire ratings so you can learn how to read a tire.
How to Read Tire Size
Aside from the tire’s brand name and model, the sidewall of your tire tells you a lot about its size and characteristics. Let’s help you crack this tire number code by reviewing each section.
Vehicle Type
At the beginning of the tire code, there will usually be the letter “P” or “LT.” The “P” tells you that it’s a P-Metric tire designed for “P”assenger vehicles such as sedans, SUVs, minivans, and light-duty pickup trucks. The “LT '' indicates that it’s a light truck tire for vehicles capable of carrying heavy loads and navigating rough terrain — i.e., heavy-duty trucks, SUVs, and vans.
Not seeing any letters? You might have a Euro-Metric tire. Euro-Metric and P-Metric tires are designed for passenger vehicles but may have different load capacities.
Width
Following the letter in the code, you should see a three-digit number, identifying the tire's width in millimeters from side wall to side wall. For example, a P215/65R15 tire number means the width is 215 millimeters. So, the bigger the number, the wider the tire.
Aspect Ratio
After the width number, there’s a slash mark followed by a two-digit number indicating the tire’s aspect ratio. What the heck does that mean? It’s the tire’s ratio of sidewall height to width. For example, a P215/65R15 tire has an aspect ratio of 65, meaning its sidewall height is 65% of its width. The bigger the aspect ratio, the larger the tire’s sidewall. Additionally, an aspect ratio of 50 or lower means the tire has a short sidewall, offering improved steering response and better overall handling.
Construction
Following the aspect ratio number, you’ll find a letter that signifies the type of internal construction maintaining your tire’s stability. It’ll most likely be the letter “R”, which stands for radial. An industry standard for the past 45+ years, a radial tire features internal ply cords that run perpendicular to the direction of rotation.
If your tire is not a radial, there are still some belted tires for trucks designated with a “B” and bias-ply tires for older vehicles designated with a “D” for the diagonal orientation of the belt.
Wheel or Rim Diameter
After the construction letter, there’s a two-digit number signifying the wheel or rim diameter in inches — the rim or wheel size measured from one end to the other. This number tells you the rim or wheel size that the tire is intended to fit. For example, a P215/65R15 is designed to fit a 15” wheel or rim.
Load Index
Following the diameter number, you may see a two- or three-digit number that indicates the tire’s load index — the maximum carrying capacity that each tire can support when properly inflated. Let’s say your tire reads P215/65R15 95H, which has a load index of 95. At first glance, you might be scratching your head, wondering what on earth that means. Luckily, you can refer to a load index chart to help you figure this out. For a load index of 95, the tire can support approximately 1521 pounds each.
Speed Rating
The final figure in a tire size code is the speed rating, which is designated by a letter. Like the load index tells you each tire’s maximum carrying capacity, the speed rating signifies the tire’s maximum speed capability. If your tire reads P215/65R15 95H, the “H” means the tire can withstand speeds up to 130 mph. Don’t see an “H”? Refer to a speed rating chart to help you determine your tire’s maximum speed capability.
Find the Right Tire Size for Your Vehicle at Your Local Jiffy Lube
Still trying to figure what size tire your vehicle needs? No worries! Visit your local Jiffy Lube®, and we’ll help you find the right tire size for your vehicle. We replace tires based on Original Equipment Manufacturer (OEM) recommendations, so you can rest easy knowing your new tires are a perfect fit for your vehicle. Also, when you come in for a tire replacement, make sure to have the steering and suspension system inspected to help protect your investment.
NOTE: Not all services are offered at all Jiffy Lube service centers. Please call ahead or check jiffylube.com to ensure the service is available at the Jiffy Lube location near you.