How to Measure Bike Tire Size: A Complete Guide (2023)

(Last updated on March 6th, 2023)

Cycling is an amazing sport that offers fun and recreation to people all over the world. It is a great way to exercise, make new friends, and explore your local area. One amazing thing about cycling is that bikes come in all shapes and sizes.

This means they can be equipped with different parts and be made to make the experience better for you. An excellent upgrade you can make is changing your tire size. One thing that many cyclists find is that tire sizes can be difficult to understand.

In this article, we’ll tell you how to understand tire sizes properly and measure tires to ensure they fit your bike properly.

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Bike frame up close.
Image credit: Robbie Ferri

Why Is it Important to Have the Correct Tires?

Having the correct tires is vital when it comes to cycling. Here’s why you want to ensure you run tires that are compatible with your bike.


Tires that are too big for your bike can wear down the frame. Tires too small can risk damaging your wheels. Having the correct size tire ensures you don’t cause yourself any issues.

They Fit

If you buy the wrong tires, there’s a strong possibility that they won’t fit when you try to change them. The last thing you want is a set of useless tires sitting in the garage at home.


Bikes are designed to be used with certain tires. If you ride a gravel bike for long journeys and go for tires a little too small, you will not get the comfort or grip you originally had. If you put tires that are too big on them, it can cause a lot of lag. Certain factors contribute to the fastness of a bike tire.


If you don’t have the correct tires for your bike, it might make it look a little bit odd. Road tires on a mountain bike aren’t a good look. The same goes for mountain bike tires on a road bike.

MTB Tire up close.
Image credit: Robbie Ferri

How to Read a Tire Size

If you want to save yourself the trouble of measuring, you can just read the tire instead. Most tires come with special codes to tell you exactly what you are looking at. Typically they are written in two different ways, and we’ll speak about these next.

Standard Code

The first thing you want to look out for is the standard code. This will come in two different numbers.

The first will be the tire diameter.

Depending on if it’s a road or mountain bike, they can be a very similar size,  according to industry standards. 700c on road bikes is 29” as far as mountain bikes go.

They are the same diameter, but because they are different disciplines called different names.

700cRoad bike standard similar to 29” in diameter
650cRoad bike standard similar to a 27.5” in diameter
650bGravel bike tire similar to 27.5” in diameter
29”Large mountain bike tire
27.5”Medium mountain bike tire
26”Small mountain bike tire

Next, we have tire width, and this is where you have loads of different options to choose from. Again like the diameter, they are referred to under different standards.


Manufacturers Code

If you can’t find the standard code above, you will find the manufacturer’s code on the tire. Although it might look complicated, it is very easy to understand when you know what the numbers mean.

The code looks like this: 28-622.

Both numbers are very important and can tell you everything you need to know about the tire. What’s great about this number is that it works across all cycling disciplines.

The first number, 28, refers to the general width of the tire, which in this case would be 28mm.


The second number is what we call the bead seat diameter. The bead seat diameter measures where the tire sits on the rim. In this case, it’s 622, equivalent to 700c road bike wheels and 29” mountain bike wheels.

62229” / 700c
58427.5” / 650b

These are only a few examples of the manufacturer’s code. The manufacturer’s code is the best way to understand a tire. It will tell you exactly what wheel the tire will fit on and the width the tire will be.

The manufacturer’s code is an excellent way to understand tires. It is especially useful when working on older bikes, as they come in awkward sizes.

Road Bike tire up close.
Image credit: Robbie Ferri

What About Measuring Yourself?

Just say your tires have no markings or are so worn down that you can’t see them. What do you do then? Well, you’re going to have to measure the tires yourself. This is much easier than you might think when following our step-by-step guide.

Step One: Remove the Wheel

If you want to make this easy on yourself, start by removing the wheel and the tire together from the frame. You will now need to get a measuring tape and sit the wheel on the floor.

Measuring tire width.
Image credit: Robbie Ferri

Step Two: Measure the Width

The first thing you need to do is measure the tire’s width. We recommend inflating the tire to ensure the measurement is fairly accurate. You must ensure it has a good shape if it’s off the wheel.

Measure from one side to the other. You will want to take the measurement in millimeters, which will be, for example, 23mm. This would equate to 23c standard code or 23 manufacturers code. 

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Measuring tire diameter.
Image credit: Robbie Ferri

Step Three: Measure the Diameter

Measure from the center of the wheel’s edge to the outside in millimeters. Take this figure and double it; this will be our ISO diameter. For example, for us, this wheel comes out at 622.

This tire is a 23-622

Bike shifter up close.
Image credit: Robbie Ferri

Considerations to Make When Measuring Tires

When measuring tires, it’s important to take a few things into consideration that you might not have thought of.

Measuring off the Rim

When measuring off the rim, the tire doesn’t hold a very good shape, especially if it’s a performance tire. You want to ensure it’s in as natural shape as it would be on the rim and double-check to ensure you have it correct.

Classic Tires

Classic wheels and tires come in sizes such as 28”. This doesn’t mean they won’t fit a 700c wheel. This is because they are different sizes, they still share the same bead seat diameter. So many modern tires actually fit classic bikes.

Wide Rims

Wider rims make your tire stretch out further. For example, putting a road bike tire on a mountain bike wheel, will measure a few millimeters more in width.

Bike wheel up close.
Image credit: Robbie Ferri


When it comes to measuring tires, the best way to do it is by understanding the codes on the side. Typically every tire has one. If you can’t make it out, the good idea is to measure it on the rim, as we spoke about earlier.

When it comes to tires on your bike, it’s good to mix them up. There are so many options on the market to choose from that can give you extra speed or comfort.

You might want to consider tubeless tires. These are filled with sealant instead of an inner tube and can self-heal. They are more expensive, but they save you lots of money in inner tubes and trouble.

Frequently Asked Questions

How do I know my bike tire size?

You can either measure the tire itself, read the numbers on the side of the old tire, or check the bike specification.

Are 26 inches the same as 700c?

No, 26” is much smaller than700c as far as tires go. 700c actually measures up to around 29”, so they are very different, and tires will not work with both.

Will any 26-inch tire fit on a 26-inch rim?

Yes, you should be fine if the internal size of the tire is compatible with the inner rim width and bike.

What is the difference between a 24 and 26-inch bike?

The main difference is the wheel size. The 24” is smaller and more suited to children’s bikes and BMX.

What is 700c in mm?

700c in mm is 622mm hence the bead seat diameter on a 700c wheel is 622.

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