Your tire size is printed on the sidewall of every tire on your vehicle

The easiest place to find your tire size is on the tire itself. Walk around your car and look at the side of any tire — you will see a series of letters and numbers stamped into the rubber. This marking includes your tire size along with load rating, speed rating, and manufacturing date. The size appears as a code like 225/65R17 or 205/55R16. You do not need any tools or special knowledge to read it; the information is right there in plain view.

If you want to check the size without going outside, your vehicle's door jamb label also lists the tire size. Open the driver's side door and look at the label on the inside edge of the door frame — it shows the recommended tire size for your vehicle, along with pressure specifications. This label reflects what the manufacturer designed your car to use, which may differ slightly from what is currently on your wheels if the tires were changed at some point.

Key Takeaways

  • Your tire size is stamped on the sidewall of each tire and consists of letters and numbers like 225/65R17.
  • The door jamb label on the inside of your driver's door shows the manufacturer's recommended tire size and pressure.
  • Your owner's manual lists the correct tire size in a specifications section, usually near the front or back.
  • The first number is width in millimeters, the second is sidewall height as a percentage, and the letter indicates construction type.

Reading the tire size code

The tire size code breaks down into distinct parts, each telling you something different about the tire. A size of 225/65R17 means: 225 is the tire width in millimeters, 65 is the sidewall height expressed as a percentage of the width, R means radial construction (the standard for all modern car tires), and 17 is the wheel diameter in inches. Understanding this breakdown helps you know what to order when you need replacements.

After the basic size code, you will often see additional numbers and letters. These indicate load index (how much weight the tire can carry) and speed rating (the maximum speed the tire is designed for). A complete marking might read 225/65R17 102H, where 102 is the load index and H is the speed rating. You do not need to memorize these, but they matter when ordering new tires — you want replacements that match or exceed what your vehicle originally came with.

Checking your owner's manual

Your vehicle's owner's manual contains a specifications section that lists the correct tire size for your car. This manual is often in your glove compartment, but if you no longer have the physical copy, you can find it online by searching your vehicle's year, make, and model plus "owner's manual." The manual may list multiple acceptable sizes if your vehicle came with different options from the factory.

The manual also explains what the numbers and letters in the size code mean, specific to your vehicle. Some manuals include a diagram showing where to find the tire size on the sidewall, which can be helpful if you are looking at a tire for the first time. This reference is particularly useful if you are comparing the current tires on your car to what the manufacturer originally specified.

Why the door jamb label and tire sidewall sometimes differ

The door jamb label shows what the manufacturer recommends for your specific vehicle. The tire sidewall shows what is actually on your car right now. These can be different if the previous owner or a shop installed different tires — perhaps a different brand, a different size within an acceptable range, or tires with different performance characteristics.

If you are replacing tires, you should generally match what the door jamb label says, not what is currently on the car. The manufacturer chose that size based on your vehicle's weight, suspension, and handling characteristics. Deviating significantly from the recommended size can affect fuel economy, speedometer accuracy, and how your vehicle handles. If you want to use a different size, check your vehicle's manual or contact the manufacturer to confirm it is safe.

What to do if you cannot find the information

If the sidewall markings are worn or illegible, or if you do not have access to your door jamb label or manual, a tire shop can tell you the current size by looking at your tires. You can also call your vehicle's dealership with your vehicle identification number (VIN) — they can look up the original tire size in their system. The VIN is printed on your registration, insurance card, and on a label inside the windshield on the driver's side.

Online VIN decoders also exist, though they vary in accuracy. A more reliable approach is to visit a tire retailer's website, enter your vehicle's year, make, and model, and see what sizes they list as compatible. Most tire shops maintain databases of factory specifications and can confirm the correct size in seconds.

Tire size versus wheel size

Tire size and wheel size are related but not the same. The tire size tells you the dimensions of the rubber; the wheel size is the diameter of the metal rim underneath. In the code 225/65R17, the 17 refers to the wheel diameter in inches. When you buy new tires, you need to know both — the tire size and the wheel size — so the new tires fit properly on your existing wheels.

If you are replacing both tires and wheels, you have more flexibility in what sizes you choose. However, staying close to the original specifications keeps your speedometer accurate and your vehicle handling predictable. A tire shop can help you understand what combinations are safe if you want to go larger or smaller than the factory setup.

Frequently Asked Questions

Can I use a different tire size than what is on my door jamb label?

You can use a slightly different size within manufacturer guidelines, but significant changes affect speedometer accuracy and fuel economy. Check your owner's manual for acceptable size ranges, or contact your vehicle's dealership to confirm a different size is safe before purchasing.

What if the numbers on my tire sidewall are faded or hard to read?

A tire shop can read the size for you by examining the tire directly. You can also check your door jamb label or owner's manual, which will show the original size. If you need to order new tires, provide the shop with your vehicle's year, make, and model and they can look up the correct size.

Does the tire size on my car now match what the manufacturer recommended?

Compare the sidewall marking on your current tires to the size listed on your door jamb label. If they match, you have the factory size. If they differ, someone installed different tires at some point. For replacements, use the door jamb label as your guide.

Why do I need to know my tire size before buying new tires?

Tire size determines whether new tires will fit your wheels and affect how your vehicle handles, brakes, and accelerates. Ordering the wrong size wastes money and may require returning them. Knowing your size ensures you get tires that work safely with your vehicle.