What Does 700×18/25c Mean? (Explained)

What Does 700x18/25c Mean?

The numbers are called wheel sizing and help you understand what kind of wheels you’re looking at.

When you understand the numbers and alphabet on your tire, your grasp of vital information about your vehicle will increase.

So you can learn about the speed rating and thermal stability and even consider an upgrade or replacement. Now, What does 700x25c mean? 

700x25c is an old French system for wheel and tire sizes. The 700 here signifies the tire’s diameter measured in millimeters, while the 25 is the width measured in millimeters. Letter C represents the bicycle tire’s width; in this instance, width refers to what the bike would appear to be when viewed from the front or the back.

What Does the 700×18c-23c Mean on the Tube?

What Does 700x18/25c Mean?

The 700×18c-23c on the tube of a tire means that the tire is 700mm wide, has an 18mm inner diameter, and a 23mm outer diameter.

The traditional sizing systems are based on measuring a tire’s outside diameter.

These measurements would usually be taken in inches (29″, 25″, etc.) or millimeters (600, 800, etc.).

The Tires Are 700×23/25C. What Does 23/25 Mean?

You see the 700×18c-23c written on the side of your bike tube, and you’re not sure what it means. Let us break it down for you.

The first number, 700, is the tire’s width in millimeters. The second number, 18, is the tire’s diameter in inches.

The letter “C” after the numbers indicates that the tire is a “city” or “commuter” bike tire.

The last number, 23/25, is the tire’s construction code. 23/25 means that the tire has a 23mm width and a 25mm diameter.

700×18c/23c Wheel/Tire Compatibility

This code identifies the wheel/tire size. In this case, the 700 refers to the wheel diameter in millimeters, while the 18c and 23c refer to the tire’s width in centimeters.

So, this tube is compatible with a wheel that is 700 mm in diameter and has an 18c or 23c width tire.

What Does 25 Mean in the Bike Tire Size 700×25c?

This label reveals the tire’s size, width, height, and rim diameter in millimeters. The first number, 700, is the tire’s width in millimeters. The ‘c’ stands for centimeters and measures tire sizes.

The second number, 18, is the tire’s height in inches. The last number, 23, is the diameter of the rim in inches.

Most bike tires have a size of 700×23c. This means that the tire is 700 millimeters wide, 18 inches (ca. 46 cm) high, and has a diameter of 23 centimeters.

How Do I Translate a Tire Description Into English?

You may have seen a number like 700×18c-23c on the side of a tire tube and wondered what it means.

This number is simply a tire’s description, broken down into three parts: the width, the aspect ratio, and the diameter.

The width is how wide the tire is in millimeters. And the diameter is the size of the wheel in millimeters.

The aspect ratio means the height of the tire’s sidewall expressed as a percentage of the width.

So, in this example, the tire is 700 millimeters wide, has an aspect ratio of 18%, and has a diameter of 23 millimeters.

Tire Sizing System

Some time ago, every country that manufactured bicycles had its peculiar tire sizing system. So, the same tires could have different sizes in various countries

In the French tire sizing system, for example, 700C is a standard to show the tire diameter, i.e The tire width is 700mm.

The letter “C” means the tire width measured on a scale from A to D. That means A is very thin, and D is broad. 

In some other systems, the width was expressed in decimal and, sometimes, fractional terms.

So, despite being the same, a particular size could mean different tire designations that could not be interchanged.

The diverse traditional tire systems brought about international discontent, affecting traded equipment and vehicles, especially among countries with uneven tire and rim systems.

So, the International Organization for Standardization (ISO) created a global tire and rim system that adopted part of the European Tyre and Rim Technical Organisation system.

The new system has two parts,

  • Bead Seat Diameter (BSD) 
  • G Height.

The Bead Seat Diameter(BSD), which is the most important, is the rim’s diameter at the beads’ seat.

It has a minimum of 0.5 mm for larger wheel-tire sies or 1.0 mm for smaller tire sizes.

If the specified numbers do not match, the tire will not fit into the rim, as it would be bigger or smaller than it. 

The sizes vary based on the height of the rim. And for the G Height, the inner rim width is measured in millimeters. It ranges from 5.35 to 6.35 mm above the nominal tire size. 

ETRTOEnglish SizeFRENCH SIZEGerman SizeRim circumference (mm)
40-63528 x 1½700B standard28 x 1½1994
38-62228 x 1-5/8 x 1½700 x 38C28 x 1½ x 1,751995
37-62228 x 1-5/8 x 1-3/8700 x 35C28 x 1-3/8 x 1-5/81995
40-62228 x 1-5/8 x 1-3/4700 x 40C28 x 1½ x 1,751995
28-62228 x 1-5/8 x 1-1/8700 x 28C700C28 x 1-1/8 x 1-3/41995
32-62228 x 1-5/8 x 1-1/4700 x 32C700C Course28 x 1-1/4 x 1-3/41995
25-62228 x 1-5/8 x 1700 x 25C28 x 1 x 1-1/41995
47-62228 x 1,75700 x 47C28 x 1,751995
28-63027 x 1-1/827 x 1-1/81978
32-63027 x 1-1/427 x 1-1/41978
25-63027 x 11978
47-55926 x 2 x 1-3/426 x 1,75 x 21755
37-58426 x 1½ x 1-3/81834
40-58426 x 1½650BStandard1834
40-59026 x 1-3/8 x 1½1854
32-59026 x 1-3/8 x 1-1/4650 x 32A1854
32-59726 x 1-1/41876
37-59026 x 1 3/8650 x 35A650A26 x 1 3/81854
25-57126 x 11854
47-50724-2 x 1-3/424 x 1,75 x 21594
40-54024 x 1-3/8 x 1½1695
32-54124 x 1-3/8 x 1-1/4600A600 x 32A1699
37-54024 x 1-3/824 x 1-3/81695
40-48922 x 1-3/8 x 1½1535
37-49822 x 1-3/8 x 1-1/41563
37-50122 x 1-3/8 B.S.R.1575
37-48922 x 1-3/81535
57-40620 x 2,12520 x 2,1251274
47-40620 x 2 x 1-3/420 x 1,75 x 21274
40-43220 x 1½1356
40-43820 x 1-3/8 x 1½1375
37-45120 x 1-3/8 B.S.R.1416
37-43820 x 1-3/820 x 1-3/81375
47-35518 x 2 x 1-3/418 x 1,75 x 21115
32-35717 x 1-1/41122
47-30516 x 2 x 1-3/416 x 1,75 x 2957
54-30516 x 2957
37-29814 x 1-3/8937
37-28814 x 1-3/8937
62-20312½ x 2-1/412½ x 2-1/412½ x 2-1/4638
23-622700 x 23C1995

The Schrader Valve

In 1891, August Shrader invented the Schrader valve. He later built the Schrader firm in 1844.

Later on, in 1893, the exclusive right of production and distribution of valves in the United States was granted to August Schrader. The Schrader valve is also known as the American valve.

The Schrader valve is simply a pneumatic valve connecting an enclosed-inner part of an object to give access to gas or air.

Schrader valves are commonly used with automobiles, motorcycles, and bicycles.

A Schrader valve is made up of a valve stem fixed on the tire through which a valve core is inserted. A valve stem can only be accessed properly by using a valve core.

The Schrader valve has specialized materials built with it to prevent leakage. And in case the valve core becomes defective.

It can always be replaced using proper equipment given to respective technicians. 


Regarding bike tires, the 700×18c-23c means that the tire is 700 mm wide and has an internal circumference of 18c-23c.

This number is just a way to measure the tire’s size, so you’ll know whether it will fit your bike or not.

Now that you know what the different numbers and letters mean, you can decide what type of tire you need. If you’re still not sure, don’t hesitate to ask for help at your local bike shop!

Josh Matthews

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