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The size of the bike tire is one of the commonly ignored aspects among the casual riders.
In most cases, riders usually go with whatever bike tire that will come along or leave the task to the local bike shop when it's time to replace or upgrade a tire.
However, if you're planning on purchasing new tires online, things can get a tad challenging. This is because it's an obvious requirement to know your bike tire size.
It doesn't help that in the early days, every country had a unique sizing system. And, the same tires would be known by different numbers in different countries.
Even worse is that tires with a similar numbering system were often marked the same.
While every tire now has the size marked outside, these numbers easily wear off. And if you don’t have the size memorized, you can have a difficult time picking the ideal tire size.
Fortunately, measuring a bike tire size is easier than you think.
And in this post, we shall walk you through one of the common methods of measuring bike tire size.
But before then, it would be prudent that we have a rudimentary understanding of the bike tire size.
A Guide to Bike Tire Sizes
Traditional Sizing Systems
The traditional sizing system was not standard and was based on the measurement of the diameter.
However, the evolution of tires and rims negated the use of this sizing system due to compatibility issues.
By then, each company had its sizing structure, and this made it particularly hard to purchase a tire.
To eliminate the inconsistencies in the sizing, ISO, create a standardized sizing system that would regulate the tire measurement.
Although bike tires are available in vastly different sizes, a majority have their diameter falling between 12-26 and 1.75-2.215 inches, respectively.
Step By Step Procedure of Measuring Tire Size
Stand your bike in an upright position or lean it on a wall.
When your bike is in an upright position, you’ll easily measure the size of the bike without the bike tipping onto you.
If you are doing it alone, we recommend that you use a retractable metal tape as opposed to a plastic tap as it’s sturdier and will leave you with a free hand.
Step two of the process is measuring the diameter of the tire.
First, place the tape against the center of the wheel.
From here, extend the tape in a straight line towards the edge of your outer tire.
Measuring the width of the tire is easy.
You simply need to take your tape and place it on the ground across the tier’s tread going in a straight direction.
The size of the width will vary greatly depending on the tire’s intended use. For instance, bikes intended for rougher terrain have a wider width, while those with a narrow width promise a smoother, faster ride.
Combining the Measurements
The final part is combining the measurement.
Standard bike sizing on the tire places the diameter first, and the width second.
Calculating the Circumference of a Bicycle Wheel
Your bike circumference is handy, especially if you are looking to calibrate your bike's speedometer, GPS or odometer.
Changing your bike tire size will provide inaccurate data.
So, regardless of whether you’ve purchased a new cyclometer or simply need to calibrate the existing one because you’ve switched tires, you’ll first need to determine the wheel’s circumference.
There’re two ways to determine the circumference of a bike tire, and this is dependent on whether you know the dimensions of the diameter.
And since we’ve already shown you how to calculate the diameter, you can easily know the circumference of your bike tire by multiplying the diameter by pi.
Pi is equal to 3.14, and the circumference of a 29-inch tire is reached by multiplying 29 by 3.14.
Using a String
The second step of determining the circumference is by using a string.
This method is only used when you don’t know the wheel’s diameter.
To measure the circumference, evenly wrap a string around the outside edges of the tire.
Mark or cut the string on the spot where the string reaches back to its straight point.
The distance from one end to the marked point is the circumference of your bike tire.
Using Wet Paint
Add a dot o wet paint on your bike tire.
Carefully push the bike in a strain line, until the bike makes the second dot.
Measure on the ground the length between the first dot and the second dot, and this should give you the circumference of your bike’s tire.
Measuring the bike tire size is hard as it initially seemed.
If you follow the above steps, you can now accurately measure your bike tire size whenever the need arises.