How to Measure Bike Wheel Size?

Do you want to get a new bike, upgrade your old one, and ensure you get the sizing right? If so, you should know that the bike wheels always have to fit either way.

Unfortunately, knowing how to measure bike wheel size can seem overwhelming to some. But the truth is that it’s not rocket science. In fact, with a few simple tools, you can do it at home.

You don’t have to use a bicycle wheel size chart to measure your bike wheels (although it will give you a good starting point). All you need are a few items and the methods we’ll show you now.

Here are three methods on how to measure bike tire size:

Table of Contents

#1: The Standard Method
#2: The ISO System
#3: The Circumference Method
Conclusion

#1: The Standard Method

Step 1: Place the Bike in an Upright Position

To measure bicycle wheel size, stand the bike on its own or ask a friend to hold it steady for you. You’ll need the bike upright to measure the bicycle rim size without hardship.

If you’re measuring your bike on your own, use sturdy steel tape so you can measure with one hand while holding the bike steady with the other.

Step 2: Measure the Radius

The wheel radius is the distance from the wheel’s center to the tire’s edge.

To measure it, place the end of the measuring tape at the edge of the tire and read the number where the center meets the tape.

If you don’t have a tape measure, you can also use a piece of string or paper. Make sure that whatever item you’re using is long enough.

Now double the figure to find out its diameter.

Step 3: Measure the Width

The width is the distance between the flat part of the tire and the tread from one side of the wheel to the other.

To measure the width of the bike wheel, place the end of the measuring tape at one side of the wheel’s tread and measure to the other side.

Again, you can use a piece of string or paper to measure the width. However, since it’s only a few inches, you can get away with using a standard ruler.

Step 4: Measure the Diameter

The diameter is the distance across the wheel. Place the end of the measuring tape on one side of the wheel and measure on the other.

You can also use a piece of string or paper to measure this, but make sure it’s long enough to reach from one side of the wheel to the other.

Step 5: Finalize Your Measurements

Congratulations! You now know the way to measure bike wheel size using the standard method. When ordering or choosing a bike size, give these calculations to the salesperson.

Your measurement list should start with the diameter, followed by the width, and then the radius.

For example, if your bike wheel’s diameter is 26 inches and width is 1.5 inches, your size would be written as 26-1.5.

#2: The ISO System

Step 1: Find Bike Tire Size Using Millimeters

The International Organization for Standardization (ISO) has a specific way of measuring bike wheels: they use millimeters to determine bicycle tire size.

To check bike tire size using the ISO method, you will need a tape measure with metric units (mm).

If you don’t have the appropriate measuring item, just convert inches to millimeters by multiplying the number of inches by 25.4.

Step 2: Prop the Bike Up

Like in the Standard Method, you must prop the bike using the wall for stability, or ask a friend to hold it. To measure the radius, use the exact instructions in the Standard Method.

Multiply the number by two to get the diameter of the bike wheel in millimeters.

Step 3: Measure the Width Using the ISO System

Use the same process in measuring the width (its tread). However, measure the width in millimeters instead of inches.

You can use bike tires of different widths on the same bicycle wheel so long as the difference isn’t too stark.

Step 4: Finalize Your Measurements

For the ISO method, you should list the width first and the diameter second. For example, if your tire’s width is 40 millimeters and the diameter is 622 millimeters, your size would be written as 40-622.

For example, the most common width for a road bike wheel is around 23, 25, and 28 millimeters, while the most common width for a mountain bike is approximately 35, 38, and 40 millimeters.

#3: The Circumference Method

Step 1: Measure the Circumference

The circumference is the distance around the outside portion of a bike tire. It extends from the bike rims round to where it meets again.

You can measure the circumference using a tape measure or a piece of string and then measure the string with a ruler.

Step 2: Multiply the Diameter by Pi

The circumference of a bike tire, or any circle in general, can be measured easily if you already know the diameter. All you have to do is multiply the diameter of the tire by pi (3.14)

For example, if the diameter of the bike tire is 28 inches, then the circumference would be 28 x 3.14 = ~88 inches.

Step 3: Use a String

Again, you can measure the circumference of the bike wheel by using a piece of string. This option is only viable when you still don’t know the diameter of the wheel.

To do this, wrap a string around the outside edge of the tire. Mark the spot of the string that meets the starting point.

Use a tape measure to determine the length of the string from the end to the mark. This will give you the circumference in inches or millimeters.

Step 4: Use the Roll Method

You can also figure out the circumference of the bike wheel by using the old-fashioned way, also known as the Roll Method. This involves simply rolling the bike wheel until it makes one complete revolution.

Use chalk or a piece of tape to mark where the bike tire first touched the ground. Then, measure from that spot to where it meets again.

This will give you the circumference of the bike wheel in inches or millimeters, depending on how you measure it. At the same time, you can also measure the diameter of the wheel since you know how far it has traveled.

Conclusion

Now that you know how to measure bike wheel size, it will be easier to find the right-size bike or tire for your needs. Since there are three reliable methods of measuring bike tire size, you won’t run out of options.

Just remember to take careful and precise measurements to avoid any errors. Accuracy is of utmost importance when measuring an MTB wheel or a child bike wheel.

With the right size, you’ll be able to enjoy your bike rides even more! So go ahead and determine bicycle tire size using the method of your choice!