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How to Measure a Bicycle Tire

how to measure a bicycle tire

Learning how to measure a bicycle tire is probably one of the most ignored skills by some bikers. Many of these bikers just tend to go with the flow and do not care about whatever there is on their bike. Usually, these bikers just tend to let the bike shop do whatever replacement or upgrade they need for the bike’s tire. But, as a biker, it is your responsibility to learn skills related to the maintenance of the bike.

Doing it on your own is more practical and economical and will give you the chance to know more about your precious investment. With this development, most tires have their measurements imprinted on the surface, but they can be unreadable overtime when the tire is worn out. For this reason, every biker needs to learn how to measure bike rim for maintenance purposes.

How to Measure Wheel Size on a Bike

how to measure wheel size on a bike

When it comes to replacing the tire of your bike, you will need to know the size of the wheels. For sure, the wheel’s size is written on the tire but worn out and aging can make it unreadable over time. So, if it happens that you need the size of the wheels, then you will need to measure it manually through the following methods below:

First Method: The Standard Method

When it comes to the standard method, the first thing to do is put your bike in a bike stand or lean it against the wall if you do not have a stand. Doing this will make you comfortable and will give you easy access to measure the size of the wheels efficiently. If it happens that you measure the bike alone, I suggest using a retractable metal tape measure since it will be more stable and sturdy to hold. Otherwise, you can use a regular plastic tape measure if you have companions during the measuring process.

  • The first thing to measure is the distance from the ground underneath the tire until the center of the wheel. The measurement should be in inches and is called the radius. Once you have the measurement, multiplied the measurement by two to get the entire diameter of the bike’s wheel.
  • The next step is to take the measurement of the flattened portion of the tire across the tread from one side to the other. The distance you measured should also be in inches and that is called the tire’s width.

After measuring the width of the tire along with the first measurement, which is the diameter of the wheel, you now have the complete set of measurements for your tire. When buying a new tire, put the diameter first, then followed by the tire’s width. But remember that the measurement of the bike tire should be in full-inch increments. Meaning, if the measurement happens to have slight over and under or under an inch, then you can do a round off to the nearest inch.

Second Method: The ISO Method

Another option in measuring tires at home is through the use of the ISO (International Organization for Standardization) system. This type of measuring system uses millimiters in measuring the size of the bike’s tire and is known for its accuracy since it will give the exact measurement.

If you do not have the measuring tape with metric rules and can only measures in inches, all you have to do is multiply the number of inches to 25.4 millimiters which is equivalent to an inch. Please note that tires are usually measure in both the standard and the ISO measuring system and the measurement should be posted on the sidewall of the bike’s tire.

  • During the measurement process, start by again putting the bike in a comfortable manner where you can easily measure the size of the tire. Use a bick stand or leaned the bike agains the wall for easy access.
  • Then, you will need to measure in millimiters the distance between the cente of the tire to the its inner edge. The measure ment will be multiplied by two to get the diameter. This measurement is called the BSD or the Bead Seat Diameter.
  • The next step is to measure the tire’s width in millimiters which is the distance of the flat tire across the tread from one side to the other.

If you happen to see a new tire measured in the ISO system, the width is listed first followed by the diameter of the tire. For example, a wheel sized of 39 x 700 should have a tread size of 39 millimiters and and a 700 millimiters diameter.


Learning how to measure a bicycle tire is also essential knowledge that every biker must know. This information is important during the proper replacement of your bike’s tire. For sure, the size of the tire can be found printed on it but can be unreadable over time. If this happens, then measuring your tire is the best way to know the measurement of the bicycle tire.

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