Check your vehicle's door jamb first

The fastest way to find your rim size is to open your driver's side door and look at the sticker on the inside edge of the door frame. This label, called the tire and loading information placard, lists the original equipment manufacturer (OEM) tire size in a format like 225/65R17. The last two digits — in this case 17 — are your rim diameter in inches.

This sticker shows what the vehicle came with from the factory. If you have replaced your rims since purchase, this number may not match what is currently on your car, but it tells you what size the manufacturer designed the vehicle to handle safely.

Read the sidewall of your current tire

If you want to know what rim size is actually on your vehicle right now, look at the sidewall of any tire currently mounted on your car. The tire size is printed in large numbers and letters. In a size like 225/65R17, the "17" at the end is your rim diameter.

You can check this without tools — just walk around your car and read the sidewall of any tire. The information is printed in white or yellow lettering and is straightforward to spot. If all four tires match, you have the same rim size on all wheels. If they differ, you may have a spare that is a different size, which is common.

Key Takeaways

  • Your vehicle's door jamb sticker shows the rim size the manufacturer intended, found by reading the last two digits of the tire size listed there.
  • The sidewall of any tire currently on your car displays its rim diameter as the last number in the tire size format.
  • Rim size is always measured in inches and appears as a whole number at the end of the tire size code.
  • If you have replaced your original rims, the door jamb sticker and your current tires may show different sizes.

Understand tire size format

Tire sizes follow a standard format that includes multiple pieces of information. A typical size reads 225/65R17. The first number (225) is the tire width in millimeters. The second number (65) is the aspect ratio, which describes how tall the tire sidewall is as a percentage of the width. The letter R means radial construction. The final number (17) is the rim diameter in inches.

Once you know this format, you can read your rim size from any tire size label in seconds. The rim diameter is always the last number, always in inches, and always a whole number without decimals.

Check your owner's manual

Your vehicle's owner's manual contains a specifications section that lists the original tire and rim sizes. This is useful if you cannot access the door jamb sticker or if you want to confirm what size the manufacturer recommends. The manual will show the rim diameter along with the full tire size.

If you no longer have a physical copy, you can often find your owner's manual online by searching for your vehicle's year, make, and model along with "owner's manual PDF." Many manufacturers also host manuals on their websites.

Measure your rim if the label is missing

If you cannot read any tire sidewall and your door jamb sticker is damaged or missing, you can measure your rim directly. Use a tape measure or ruler to measure across the rim from one inner edge to the opposite inner edge, passing through the center. This measurement in inches is your rim diameter.

This method is less precise than reading a label because rims can have slight variations, but it gives you a close approximation. If you are buying new tires or rims and need an exact size, use one of the label-reading methods instead.

Why rim size matters

Rim size affects which tires you can purchase, how your vehicle handles, and your speedometer accuracy. Using a rim size that differs significantly from the manufacturer's recommendation can cause your speedometer to read incorrectly and may affect your vehicle's suspension and braking performance.

If you are shopping for new tires or rims, knowing your current size is the starting point. Tire shops and rim retailers will ask for this number, and having it ready speeds up the process of finding compatible options.

Frequently Asked Questions

Is the rim size the same as the wheel size?

Rim size and wheel size are often used interchangeably, but technically the rim is the metal part that holds the tire, while the wheel includes the rim plus the hub and other components. For practical purposes, when someone asks your wheel size, they mean the rim diameter — the number you find at the end of the tire size code.

Can I use a different rim size than what the door jamb sticker says?

You can use different rim sizes, but only within a narrow range that keeps your overall tire diameter close to the original. Changing rim size significantly can affect speedometer accuracy, fuel economy, and handling. Tire shops can tell you which alternative sizes are safe for your vehicle.

What if my tires show different sizes?

If your tires show different sizes, you likely have a spare tire that is smaller than your regular tires, which is normal. All four tires that touch the road should be the same size. If they are not, you may have a mismatched set that should be replaced together.

Do I need to know my rim size before buying new tires?

Yes. Tire size must match your rim size exactly. When you order tires, you provide the full tire size, which includes the rim diameter. Giving the wrong rim size will result in tires that do not fit your wheels.