Where to find your tire size right now
Your tire size is printed on the sidewall of every tire on your vehicle, stamped into the driver's side door jamb, and listed in your owner's manual. The sidewall is the fastest place to look if you are standing next to your car. The door jamb is the most reliable if you want the size your vehicle left the factory with. Your manual is the best reference if you need to understand what the numbers mean.
You do not need any tools or special knowledge to read a tire size. It takes about two minutes once you know where to look.
Key Takeaways
- Tire size is printed on the outer sidewall of each tire in a format like 225/65R17, which you can read without removing the tire.
- The driver's side door jamb (the edge of the door frame where it closes) shows the original tire size your vehicle was built with.
- If your tires are different sizes or you have replaced them, the sidewall shows what is actually on your car right now.
- The numbers break down as width in millimeters, sidewall height as a percentage, construction type, and wheel diameter in inches.
Reading the sidewall of your tire
Walk to any tire on your vehicle and look at the outer edge facing away from the car. You will see a series of numbers and letters stamped into the rubber. The tire size appears as the first set of characters, usually near the top of the sidewall. It looks like this: 225/65R17.
The format is always the same. The first number (225) is the tire width in millimeters. The second number (65) is the sidewall height as a percentage of the width — so a 65 means the sidewall is 65% as tall as the tire is wide. The letter (R) means radial construction, which is standard on all modern passenger vehicles. The final number (17) is the wheel diameter in inches.
Write down or photograph this exact sequence. If you have four different tires on your vehicle, check each one — they should all match, but it is worth confirming. If they do not match, you have a mixed set and should address that before your next tire rotation.
Checking the driver's side door jamb
Open your driver's side door and look at the frame where the door closes — this is called the door jamb. You will see a sticker or placard attached to the inside edge, usually at about waist height. This label is called the tire and loading information label.
The label shows the tire size your vehicle was manufactured with, the recommended tire pressure for front and rear tires, and the maximum weight your vehicle can carry. The tire size here is the factory specification. If you have replaced your tires with a different size, this label will not match what is on your sidewall — that is normal and usually fine, as long as the new size is within the approved range for your vehicle.
Photograph this label or write down the tire size and pressure numbers. You will need the pressure information when you check your tire pressure, and the tire size here is useful if you want to know what your vehicle originally came with.
Finding tire size in your owner's manual
Your vehicle's owner's manual contains a section on tires, usually near the back or in a maintenance chapter. The manual lists the original tire size, explains what each number and letter means, and often shows a diagram of where to find the information on the sidewall.
If you have lost your physical manual, you can find a PDF version online by searching for your vehicle's year, make, and model plus "owner's manual." Many manufacturers host these for free on their websites. The tire section will confirm what you read on the sidewall and explain whether you can use different sizes if you need to replace your tires.
Understanding what the numbers mean
A tire size like 225/65R17 breaks down into four pieces of information. The width (225) is measured in millimeters from sidewall to sidewall. A wider tire grips better in dry conditions but can hydroplane more easily in wet weather. A narrower tire is often better in snow and rain.
The sidewall ratio (65) is the height of the sidewall as a percentage of the width. A higher number means a taller sidewall and a softer ride. A lower number means a shorter sidewall, a firmer ride, and usually better handling. This number also affects your speedometer accuracy — changing it significantly can make your speedometer read incorrectly.
The construction type (R) is almost always R for radial. This refers to how the tire's internal layers are arranged. Radial tires are standard on all modern cars and trucks.
The wheel diameter (17) is measured in inches. This must match your wheel size exactly. You cannot put a 17-inch tire on a 16-inch wheel, and you should not mix wheel sizes on the same vehicle.
What to do if you cannot find the size
If the sidewall is too worn or dirty to read, clean it with a damp cloth and look again. If the text is still not visible, the tire is very old and should be replaced regardless. You can also check the door jamb label or your manual instead.
If you have aftermarket wheels and tires that are a different size than the original, the sidewall will show the current size. The door jamb will show the factory size. Both are correct — they are just describing different things. Use the sidewall size when you are buying new tires or checking pressure, because that is what is actually on your vehicle.
Frequently Asked Questions
Can I use a different tire size than what is on the door jamb?
You can use a different size if it is within the approved range for your vehicle, which your manual lists. Common approved sizes differ by only one step — for example, if your factory size is 225/65R17, you might be able to use 225/60R17. Changing the size significantly affects your speedometer, fuel economy, and handling. Check your manual or ask a tire shop before switching.
What if all four tires show different sizes?
This usually means you have replaced tires one or two at a time instead of all four together. You should replace all four tires at the same time with the same size and brand when possible. If you have mixed sizes, have a tire shop inspect them to make sure they are safe to drive on.
Do I need to know my tire size before I buy new tires?
Yes. Write down the size from your sidewall or door jamb before you shop. You can also bring a photo of the sidewall or the door jamb label to the tire shop. The shop will confirm the size is right for your vehicle, but you need to know it first so you can compare prices and options.
What does the load index and speed rating mean?
The load index (a number like 95) tells you the maximum weight each tire can carry. The speed rating (a letter like H or V) tells you the maximum speed the tire is rated for. Both appear on the sidewall after the wheel diameter. Your door jamb label shows the recommended load index for your vehicle. You should match or exceed this number when you buy new tires.