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What Does The ā€œCā€ In Bike Tire Sizing Really Mean?-Here’s what you need to know

The alphabet C is not a sign about describing tire sizes and widths based on different countries, it is simply a french sign which is almost seen on every bike tire, even the same width tires have the alphabet C but these same width tires are different and not interchangeable with each other. this alphabet is not an exact sign for an exact width and tire size. it is a simple term that is misleading by tire companies and there is no rocket science or any genuine fact behind this alphabet on bike tires.

The alphabet C is simply a historical relic, let’s give an example if there are two tires,  both are different in a single C alphabet,(700c by 25 and 700 by 25c), these are two numbers both are same but the C is different with both numbers, and you want to buy a single number tire for your bike, first, you will start searching on the internet about the real and genuine difference between both of them. you will find different prices for both of them, this price difference is not due to the alphabet C but it is the difference of the rubber and material of the tires between these numbers, it means the alphabet C is not going to bring a noticeable change in bike tires.

The alphabet C also described the width of the tires in the past, there were four different alphabets that were included in the characteristics and properties of tires and these four alphabets were (a,b,c,d). those tires which had alphabet A written on their side walls were narrow tires and alphabet B tires were a little bit wider than the Alphabet A tires Alphabet C tires were wider tires and alphabet D was the widest size of tires. but it was the old discovery, nowadays tires are measured in millimeters.

ISO( International Standard Organization):

It is an international organization and it leads more than 170 countries, when asked by this organization about the alphabet C related to tire sizes, there was no confirmed report on this alphabet even some countries would never know about the alphabet C of bike tires. as a result it was concluded that these C alphabet tires were manufactured and in France and these were exported to other countries and there was no fact behind this alphabet related to sizing of bike tires.

Does C Alphabet mean Centimeters?

No the alphabet C on bike tires does indicate and measure tire size in centimeters, it’s simply a sign which described the width of the tires in past.

The Alphabet C Indicates Bead Seat Diameter Of Bike Tires:

The alphabet C describes the diameter of bead seating of bike tires which means if the tire has written on its sidewalls 700c number, then on actual basis, 700c tire means the inner diameter of these tires is 622 millimeters. and also if you see the number 25 with the alphabet C (25C), then it also describes the diameter of the tire in millimeters.

Are 700C tires of 700 millimter?

Riders and bikers start thinking about the 700cv tires that are 700 millimeters, no 700 c tires do not mean that these tires have a width and diameter of 700millimter. the diameter of the tire regarded to tire sizes is given below to explain clearly.

  • Tires with a diameter of 622 millimeters are 24.50 tire sizes.
  • Tires with a diameter of 630 millimeters are 24.80 tire sizes.
  • Tires with a diameter of 685.8 millimeters are 27 tire sizes.
  • Tires with a diameter of 700 millimeters are 27.58 tire sizes.
  • Tires with a diameter of 736 millimeters are 29 tire sizes.

Now I have explained above in the article, according to ISO 700c tires have 622 millimeters of width and diameter, according to the tire sizes and millimeters 622-millimeter tires sizes are really smaller with 24.5 tire sizes. but this 700c with 622-millimeter tires was a past theory, nowadays if you want to know information about the 700c tires then these are the larger tires with 27 tire sizes. it shows that the tire sizing and diameter, width varies and changed from the past french historical relic.

Although this discussion of the alphabet C and tire sizes in millimeters and diameters was different in different countries, even some countries would not know about this tire sizing, the reason is that different countries make tires and their tires contain their own lettering like a,b,c and d and when this tire is shipped to another country, this country is not aware of these numbers, because the next country is also making and manufacturing its own tires with its own different alphabets divided for different tire sizes. based on this discussion, the alphabet C has different meanings and different tire sizes in different countries, that’s why I have described in the first line of my article, that the alphabet C does not matter for bike tires in sizing.

In the end, According to Sheldon brown theory:

If there are two tires that are of equal sizes and there is no noticeable change between them, but both are described in different mathematical forms, one tire is expressed in decimal and the other tire is expressed in fraction form, these two tires are not compatible with each other and you would change one of them with the other on the same rim.