The tire size is printed on the sidewall of your tire in a series of numbers and letters
Every tire has its size stamped into the rubber on the side — the part that faces outward when the tire is mounted on your wheel. You do not need tools or special knowledge to read it. The size appears as a code like "225/65R17" or "P195/60R15", and it tells you the tire's width, profile, construction type, and wheel diameter. This information is the same on all four tires if they match, or it may vary if you have different sizes front and back.
The sidewall also holds other useful details: the load rating (how much weight the tire can carry), the speed rating (the maximum safe speed), the tire's age, and the manufacturer's name. But the size code is the most prominent marking and usually appears in white or raised lettering.
Key Takeaways
- The tire size is printed on the outer sidewall of the tire in a code format like 225/65R17.
- The first number is the tire width in millimeters, the second is the sidewall height as a percentage of width, R means radial construction, and the last number is the wheel diameter in inches.
- You can read the size without removing the tire — just look at the side of the tire facing outward when it is on your vehicle.
- The sidewall also shows the load index, speed rating, manufacturing date, and tire brand, all useful for maintenance and replacement decisions.
How to read the tire size code
The tire size code breaks down into four parts. Take "225/65R17" as an example. The first number, 225, is the tire width in millimeters — how wide the tire is from one sidewall to the other. The second number, 65, is the sidewall height expressed as a percentage of the width. So a 65 percent sidewall on a 225-millimeter tire means the sidewall is about 146 millimeters tall. This ratio affects how the tire rides and handles.
The letter R stands for radial construction, which is the standard for all modern car tires. The final number, 17, is the wheel diameter in inches — the size of the rim the tire fits onto. So a 225/65R17 tire is 225 millimeters wide, has a sidewall height of 65 percent of that width, uses radial construction, and fits a 17-inch wheel.
Some tires have a letter at the very beginning, usually P or LT. P means passenger vehicle, and LT means light truck. This letter tells you the tire's load capacity and speed rating category. If your tire code starts with P, it is designed for cars, sedans, and crossovers. If it starts with LT, it is built for trucks and heavier loads.
Where exactly to look on the tire
Stand next to your vehicle and look at the outer edge of the tire — the part you see when you look at the wheel from the side. The size code is printed on the sidewall, usually in white lettering or raised text. It runs vertically or at an angle along the rubber. On most tires, the size appears near the top of the sidewall, between the tread and the wheel rim.
If you cannot see it clearly from standing height, crouch down or use a flashlight. The lettering is permanent and will not wear off, even after thousands of miles. If your tire is very dirty, wipe the sidewall with a cloth to make the numbers easier to read.
You do not need to remove the tire from the vehicle to find the size. All four tires will have the code printed on them, so you can check any tire that is convenient to reach.
Other important markings on the sidewall
Below or near the size code, you will see the load index and speed rating, usually shown together as two characters like "95H" or "100V". The load index is a number that corresponds to the maximum weight the tire can safely carry — higher numbers mean higher weight capacity. The speed rating is a letter that indicates the maximum speed the tire is rated for. H means up to 130 mph, V means up to 149 mph, and W means up to 168 mph. Match these ratings to your vehicle's needs; using a tire with a lower rating than your vehicle requires can be unsafe.
You will also find the tire manufacturing date printed as a four-digit code, usually near the load and speed ratings or on the opposite sidewall. The code looks like "2419", which means the tire was made in the 24th week of 2019. This date matters because tires degrade over time even if they are not driven. Most experts recommend replacing tires that are 10 years old or older, regardless of tread depth.
The sidewall shows the tire brand name, the specific model name, and sometimes a traction rating or temperature rating assigned by the U.S. Department of Transportation. These ratings help you compare tires when you are shopping for replacements.
Why you need to know your tire size
Knowing your tire size is essential when you need to replace a tire or buy new ones. You cannot order a replacement without the exact size code. If you buy the wrong size, the tire will not fit properly, which affects handling, fuel economy, and safety. The size also determines the correct air pressure for your tires — different sizes have different pressure requirements.
Your vehicle's owner manual lists the recommended tire size, but the sidewall is the fastest way to confirm what you currently have. If you ever need to describe your tires to a mechanic, a tire shop, or an insurance company, the size code is the first piece of information they will ask for.
What to do if the size is hard to read
If the sidewall lettering is worn, faded, or covered in dirt, clean the tire with soap and water or a damp cloth. Most lettering remains visible even after years of use because it is molded into the rubber. If you still cannot read it clearly, try taking a photo with your phone's flash — the light often makes faded lettering stand out.
If the sidewall is damaged or the lettering is genuinely illegible, you can find your tire size in your vehicle's owner manual or on a placard inside the driver's door jamb. The door jamb placard lists the recommended tire size and pressure for your specific vehicle. You can also contact your vehicle's manufacturer or a tire shop with your vehicle's year, make, and model, and they can tell you what size tires your car came with.
Frequently Asked Questions
Do all four tires have the same size?
Most vehicles have the same size on all four tires. Some performance or all-wheel-drive vehicles use different sizes front and back, so check each tire. The placard on your driver's door jamb will tell you if your vehicle uses different sizes.
What does the R in the tire size mean?
R stands for radial construction, which is how the tire's internal layers are arranged. All modern car tires are radial. You may see D (diagonal) on very old tires, but radial is the standard for safety and fuel economy.
Can I use a different tire size than what is on my vehicle now?
You should use the size listed in your owner's manual or on the door jamb placard. Using a significantly different size can affect speedometer accuracy, fuel economy, and handling. Minor variations within the same load and speed rating are sometimes possible, but check your manual first.
Where is the manufacturing date on the tire?
The four-digit date code is printed on the sidewall, usually near the load and speed ratings or on the opposite side from the main size marking. The first two digits are the week, and the last two are the year.
What if I cannot find the size code on my tire?
Check both sidewalls — the code appears on at least one side of every tire. If the sidewall is damaged or illegible, look in your vehicle's owner manual or on the placard inside the driver's door jamb for the recommended size.