how to measure bike tire size

How to Measure Bike Tire Size – In 5 Easy Steps

If you love to get out on two wheels but want to make sure your bike’s tires are always at the optimal pressure, it’s important that you know how to measure bike tire size, but it can be tricky to understand tire size. After all, most bikes require a different size for each of their tires.

Usually, the size of the bike tire is one of the most ignored parts of the bicycle. Usually, the riders don’t even care about what size their cycle tire is, and when they needed to upgrade it, they leave the work to local like shop.

But when it comes to making the purchase online, usually everyone finds it a bit challenging, and why wouldn’t it be challenging, we all know the model and name of our bike, but no one even cares to know about the size of the tire.

So what is bike tire size? And how do we measure it? Bike tire sizes are given in inches and millimeters (mm) and measured from the rim of the wheel to the valve stem on the inside of the wheel.

Tires come in a variety of diameters, but the most common are 23×1.75 (25mm) and 28×1.5 (28mm). There are also 5-6 inch wide tires, though that’s more for show than actual riding.

So lets us know how to measure bike tire size and what are the standards used in the measurement of our tires.

How to Read Bike Tire Sizes

It’s important to note that tire sizes are written slightly differently in the US and throughout the rest of the world. In America, it’s common for tires to be measured from wall to wall (width), while in most of the world, they’re measured from rim size (width). This can cause a lot of confusion. If you can’t find your size on your bike tire depth tread chart, try searching with both measurements, so you get results no matter how your tire is labeled.

For example, if you’re looking for a 23×1 1/8 inch (25mm) tire, you’ll find plenty of results from 25mm to 27mm. The best way to know for sure is to measure your current tires. That way, you’ll make sure you’re buying the right size tire no matter what it says on the outside of the rim.

Tire Size Marking Schemes

Before going into the tire measurement process, it’s important to clear some of the confusion. There are various standards followed for the bicycle tires measuring.

When you make your tire purchase, you will see the size labeled in:

  • ETRTO standard (measured in mm)
  • English standard (measured in inches)
  • French standard (measured in mm but not shown on your MTB tires)

For more details of the above labeling scheme, check the image below with a proper comparison of all the 3 types of size markings. The image is taken for reference from Wikipedia.

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ETRTO (ISO) Vs. Inch Vs. French Scheme

If you are not able to understand the above measurement properly, then look at the values in the table given below for a more detailed explanation of the image above.

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Size Marketing Scheme Table

I know it’s a bit difficult to take on, but it’s important to know so that you won’t end up buying a tire of a different size for your bicycle.


To clear up the confusion once and for all, ISO – the International Standards Organization – has set a standard that manufacturers must follow in order to market their tires around the globe. Both measurements are accepted, but one measurement will always be converted into the other. So if you’re looking for a 23×1-3/8 tire (ISO designation), you can also write it as 25×1 1/8 (American designation).

The difference between ISO and American tire sizing is really just a matter of preference. If you’re looking to buy new tires for your bike, you’ll want to measure the current ones so that you know exactly what size to look for.

How to Measure Bike Tire Size?

With the ISO system in mind, here’s how you measure a tire:

Step 1: Place your Bike Upfront on Stand

The very first step is to put your bike in an upfront position so that it can ease your process in the measurement of the tire easily. You can also keep your bike on its kickstand or make it stand against the wall, whichever one you feel like easy for you.

Step2: Determine the Diameter Of your Bike Tire

Measure the diameter of the tire’s rim with a tape measure from inside edge to inside edge. That means you need to perfectly calculate the diameter of the tire from the inside.

Step 3: Measure the Tire Width

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Measuring the Bike Tire Width Properly

Measure the width of the tire at its widest point. that means your need to measure the width of the tire’s rim from outside edge to outside edge so that you will get the perfect possible result.

Step 4: Combine the Result

Now the only thing left is to combine the results that is the diameter and width of the tire. for eg, if the diameter you got is 26 inch and the width say 2.2 inch then the marking on the tire will be 26×2.2 but remember that if you calculated the values in inches than you also need to convert it to the ISO standard, because you will also find many tires online in ISO format.

We have already discussed about all the standard formats used in the tire measurement above, hope that helps. Also if you are looking to change the RIM size of the tire, you need to follow the guide given below to know how it works.

Does RIM Size Matter?

One of the confusion that might come to your mind if that whether buying a bike tire with a different RIM makes a difference?

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Understanding the RIM Sizing

Look at the image above, all the bike tires in the above image are 26″ tires, but each of them has a different rim size. So it’s important to measure the outer area of the tire accordingly and not up to the rim otherwise, you will end up getting a smaller or bigger tire.

As for the rim size, it doesn’t matter the size of the rim, you can use whatever size you like, don’t keep in mind the overall circumference of your bike wheels.

How to Buy Bike Tires

Buying tires online can be tricky. When you’re sizing up your tires, make sure you’re getting the right fit for your bike. If you’re not sure which tire size is right for your bike or have questions about what type of tire to get, don’t hesitate to contact us, and we’ll be happy to help!

Otherwise, measure the circumference of your wheels (taking into consideration if they’re ISO-compliant) and buy a tire that perfectly matches. Then you’ll never have to worry about your tires being under or overinflated.

More about Bike Wheel Size

If you are still confused about the measurement of your bike wheel size & how to measure bike tire size properly, check out the youtube video below to know all the basics about bike tire sizing.

Piece of Advice

It’s always important to know the size of your bike tire so that you know whats the exact pressure is when you put air in bike tires, this will keep you from underinflating or overinflating your bike tires.

Also remember, that it’s not important that you get the exact tire size for your bicycle. Even if you end up getting a bit smaller or bigger tire, it will fit easily in your bicycle. In some cases, if you are planning on getting much wider tires, then you might need to get wider rims as well to accommodate the tires.

So if you are looking for upgrading your bike tires, measure the current tire size and upgrade accordingly.

Have a Wonderful Cycling Ahead! 😊

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