When you glance at the sidewall of your car’s tire, you’ll see a mix of letters and numbers. While it may look like a random code, each part of that sequence actually provides important information about your tire’s size, load capacity, speed rating, and more. Understanding this code can help you make smarter decisions when it’s time to replace your tires or check for compatibility.
Here’s what those numbers and letters really mean and why they matter for your vehicle.
Tire Type (First Letter)
Most tire codes start with a letter that indicates the type of vehicle the tire is designed for.
- P stands for Passenger vehicle.
- LT stands for Light Truck.
- T is for Temporary (spare tires).
If there’s no letter, it’s usually a European tire standard for passenger vehicles. Using the correct tire type is essential for proper load support and handling.
Tire Width (First Three Numbers)
The next part of the code, typically three digits, refers to the width of the tire in millimeters. For example, if the code starts with P215, that means the tire is 215 millimeters wide from sidewall to sidewall.
Wider tires provide more grip and stability but may affect fuel efficiency. The ideal width depends on your vehicle’s specifications and driving needs.
Aspect Ratio (Following Two Numbers)
After the width, you’ll see a slash and a two-digit number, such as /60. This is the aspect ratio, which represents the height of the tire’s sidewall as a percentage of the tire’s width.
A 60 aspect ratio means the sidewall height is 60 percent of the width. Lower aspect ratios usually indicate performance tires with a stiffer ride, while higher numbers suggest a more comfortable, cushiony ride.
Construction Type (Single Letter)
Next in the sequence, you’ll often see a letter like R, which stands for Radial construction. This is the most common type and means the internal layers of the tire run radially across the tire.
Other, less common types include B for bias-ply and D for diagonal. For most modern vehicles, radial construction is standard and preferred for stability and durability.
Wheel Diameter (Next Two Numbers)
Following the construction type is a two-digit number like 16, which tells you the diameter of the wheel (rim) in inches. So, if the code says P215/60R16, that tire fits a 16-inch wheel.
Choosing the right wheel diameter is crucial for proper fit. Mismatched tire and wheel sizes can affect ride height, speedometer accuracy, and handling.
Load Index (Next Two or Three Digits)
The load index is a number that indicates how much weight each tire can safely carry. For instance, a load index of 94 corresponds to 1,477 pounds. You’ll need to look up the load index chart to get the exact weight capacity for your number.
Choosing a tire with too low of a load index can cause overheating and premature failure, especially when hauling heavy loads or driving long distances.
Speed Rating (Final Letter)
The final letter in the sequence, such as H, V, or T, tells you the maximum speed the tire can safely sustain. For example:
- T = 118 mph
- H = 130 mph
- V = 149 mph
While you may never drive at these speeds, using tires with the appropriate speed rating ensures stability, especially at highway speeds or in performance applications.
Why This Information Is Important
Tire codes help ensure that your vehicle handles properly, stops safely, and meets performance expectations. When replacing tires, always match or exceed your vehicle’s original specifications. Using the wrong size or type can lead to uneven wear, poor fuel economy, or reduced traction in certain conditions.
If you’re considering upgrading your tires for better performance, off-road capability, or a smoother ride, understanding the code is the first step in making the right choice.
Need Help Choosing the Right Tires? Visit Diamond Head Motors Ltd in Squamish, BC
At Diamond Head Motors Ltd, we help drivers find the right tires for their vehicles and driving conditions. Whether you’re looking for all-season tires, winter tires, or performance options, our team will explain what all those letters and numbers mean and make sure you drive away with the perfect fit.
Stop by today and let our technicians take the guesswork out of tire selection. Your safety and comfort start with the right set of tires.
