How to Read Your Tire Size

Tire shopping doesn’t have to be confusing—once you crack the code, it’s easy. If this is the first time you’ve had to buy new tires, knowing your tire size is one of the most important factors in choosing the right set. Tire size affects everything from handling to fuel efficiency to ride comfort, and safety. Choosing the wrong size could mean a bumpy ride—or worse, damage to your vehicle.

Thankfully, once you understand what all those letters and numbers mean, shopping for tires becomes a whole lot easier. This guide will help you read and understand your tire size with confidence. But remember that you can always visit your local Trail Tire, and we can help you find the perfect tire for your vehicle.

Where to Find Your Tire Size

Before you can decode your tire size, you need to find it! There are a few common places you can check:

Sidewall of Your Tire: This is the easiest place to look. You’ll see a series of numbers and letters stamped right into the side of the tire—something like P225/65R17.

Driver’s Side Door Jamb: Open your driver’s side door and look for a sticker on the inside edge or the door frame. It lists the recommended tire size, load rating, and tire pressure for your specific vehicle.

Owner’s Manual: Flip to the tire section—your vehicle’s recommended tire size will be listed there.

Breaking Down the Tire Size Code

Let’s take this example: P225/65R17

Here’s what each part means:

1. Tire Type – “P”
P stands for P-metric, which means it’s made for passenger vehicles.

If you see LT, it means Light Truck, made for heavier loads and towing.

Some tires don’t have a letter at all, and those are typically Euro-metric.

2. Tire Width – “225”
This number is the width of the tire in millimetres, measured from sidewall to sidewall.

In this case, the tire is 225mm wide.

3. Aspect Ratio – “65”
This is the height of the sidewall as a percentage of the tire’s width.

A 65 aspect ratio means the height is 65% of the tire’s 225mm width.

4. Construction – “R”
R stands for Radial construction, which is how nearly all modern tires are built.

You might rarely see D (Diagonal) or B (Bias Belt), but those are mostly for specialty or vintage vehicles.

5. Wheel Diameter – “17”
This tells you the diameter of the wheel (or rim) that the tire fits, in inches.

So, this tire fits a 17-inch wheel.

Example in Action:
P225/65R17 = Passenger tire, 225mm wide, sidewall is 65% of the width, radial construction, fits a 17″ wheel.

Pro Tip: Don’t Guess It—Check It!

If you’re replacing tires, don’t assume your current tires are the original size. Always double-check the manufacturer’s recommendation—especially if you bought the vehicle used.

Final Thoughts

Knowing how to read your tire size helps you buy the right tires for your vehicle and driving style. It’s one small detail that makes a big difference in performance, safety, and comfort on the road.

Ready to roll? Grab your tire size and start shopping with confidence.

Still unsure? Your local Trail Tire can help you find the perfect match.