- By: James Grear
- Last updated:
So you’ve got a pair of 700c bike wheels and are trying to figure out which tires and inner tubes you need.
In this short guide, we explain how to convert 700c to inches for bike wheels and provide info on what 700c means on bike wheels.
Towards the middle of the article, we include a 700c tire size chart, where you’ll find accurate stats for converting different 700c tires to inches and centimetres.
If you don’t yet know what size wheels you have, we advise reading our quick step-by-step guide first, which explains how to measure a bike wheel for tire and tube sizing.
A Brief Introduction to 700c Wheels
700c wheels have been around for many years and are utilised by almost every road and hybrid bike.
But the 700c wheels you’d find on a road bike are drastically different from what you’d see on a hybrid, so why are they called 700c wheels?
The name “700c” is almost redundant now since there are so many different 700c wheels and tires available.
The “700” section refers roughly to the outer diameter of the wheel’s tire.
Many tire types are available, and a tire’s characteristics, such as tread and anti-flat protection, will impact its diameter.
Many tire types are available, and a tire’s characteristics, such as tread and anti-flat protection, will impact its diameter.
The “c” comes from old French Tire sizing and has remained on bike wheels, despite not meaning anything anymore.
The lettering in French Tire Sizing ranged from A to D and referred to the tire’s width, but this scale is now redundant.
The consistent measurement across all 700c tires is their bead seat diameter or BSD. The BSD is the diameter across the tire bead seating points inside the wheel’s rim.
The bead seat diameter (BSD) of all 700c wheels is 622mm.
You’ll see 622 alongside another number on the wall of most 700c tires.
This is known as the ISO (International Organisation for Standardisation) measurement.
A road bike’s slim tires might have an ISO measurement of “23 – 622”; the first number refers to the width of the tire when fully inflated, and the second is the BSD.
Where hybrid bikes typically use wider tires, you’ll may find a reading along the lines of “45 – 622”.
Below is a quickfire table on the common widths you can expect to see on different 700c bike tire types, first as you’ll find in millimetres and then translated to inches.
If you want to view our accurate rim width to tire size chart, you can view this towards the bottom of the article here.
| Bike Type | Common Tire Width Range | |
|---|---|---|
| Road Bike | 23 - 28mm | 0.9 - 1.1" |
| Cyclocross Bike | 28 - 35mm | 1.1 - 1.4" |
| Gravel Bike | 35 - 45mm | 1.4 - 1.8" |
| Hybrid Bike | 35 - 45mm | 1.4 - 1.8" |
Now that you understand a bit more about 700c wheels and tires, we’ll take a look at the easiest way to convert 700c to inches!
700c to Inches Explained
The most straightforward answer to “700c to Inches” is that 700c equals 27.5 inches.
But unfortunately, as you’ll see in the table below, it’s not as straightforward as that.
If you buy a random set of 27.5″ tires, they may not fit your bike, as wider tires require more clearance.
For example, if you’re riding a high-end road bike, you won’t be able to use 700 x 47c tires.
Tires this wide might fit on your wheel, but they’d probably chafe against your frame or be completely incapable of rolling.
For an accurate conversion from 700c to inches, you’ll find the diameter of each 700c tire size converted to inches and centimetres in the table below.
If you don’t currently have tires on your wheels and need to know what tire size you require, find out using our simple bike tire size guide.
| Tire Size | ISO Size | Tire Diameter (Inches) | Tire Diameter (Centimeters) |
|---|---|---|---|
| 700 x 18C | 18-622 | 25.94 | 65.89 |
| 700 x 19C | 19-622 | 26.06 | 66.2 |
| 700 x 20C | 20-622 | 26.14 | 66.39 |
| 700 x 23C | 23-622 | 26.27 | 66.72 |
| 700 x 25C | 25-622 | 26.38 | 67 |
| 700C Tubular | - | 26.69 | 67.8 |
| 700 x 28C | 28-622 | 26.8 | 68 |
| 700 x 30C | 30-622 | 26.9 | 68.3 |
| 700 x 32C | 32-622 | 27 | 68.6 |
| 700 x 35C | 35-622 | 27.17 | 69 |
| 700 x 38C | 38-622 | 27.32 | 69.39 |
| 700 x 40C | 40-622 | 27.57 | 70.02 |
| 700 x 44C | 44-622 | 28.01 | 71.14 |
| 700 x 45C | 45-622 | 28.1 | 71.37 |
| 700 x 47C | 47-622 | 28.42 | 72.19 |
What Size Tire for 700c Wheels?
So, now you understand 700c to inches measurements, we’ll need to determine which size tire will fit your wheels.
Below, you’ll find two different methods to determine your tire size for 700c wheels.
First, if your wheel has old tires on it, we’ll use them to help us distinguish the most suitable tire size.
And if your wheel has no tire on it, don’t worry. We can use a simple trick to determine what tire width you should go for.
Method 1 - Find Tire Size Using an Existing Tire
You’re in luck if your old tires are still attached to your wheels.
Tire walls provide multiple markings that will give us the information required to determine what replacement tire size you’ll need.
Looking at the tire wall, you’ll want to keep an eye out for one of two different markings.
Firstly the ETRTO (European Tire and Rim Technical Organization) marking can be used to determine a suitable replacement tire size and will follow the lines of something like “700 x 23c.”
Otherwise, the ISO marking can also be used to determine a suitable size for your replacement tires and will read along the lines of “23 – 622” (as found on this tire wall).
As you can see in the image here, both sizes refer to the same size tire and are simply two separate units of measurement.
You’ll remember from the beginning of this post that the smaller number used by both ETRTO and ISO denotes the tire’s width.
The larger number from the ETRTO measurement, in this case, “700”, refers to the tire diameter, whilst the ISO’s larger number refers to the wheel’s bead seat diameter.
Once you’ve found either of these measurements, replacing the tires is as easy as googling your ETRTO or ISO measurements and selecting whichever tire takes your preference.
Method 2 - Find Tire Size Without Existing Tires
Whilst many wheels will display measurements on the rim (as seen in the image below), an old wheel might be missing this information, making it difficult for you to know which tire size you need.
But don’t worry. There is a simple and effective method you can use to accurately determine the correct tire and inner tube size.
If you’re riding a full-size road bike, ninety-nine times out of a hundred, it will use 700c wheels. So unless it’s a kids’ bike or if you know it’s smaller, we can almost be sure that it uses 700c wheels.
If you want to double-check this figure, you’ll want to measure the wheel’s BSD, from braking surface to braking surface (As shown in this image)
If this measurement comes in at 622mm, or 24.5″, it’s a 700c wheel.
Next, you’ll want to measure the width from the inside of your rim. Use a tape measure or ruler to measure this width, making sure to measure from the inside, rather than the outside of the rim (as shown in the image below).
Once you’ve taken this measurement, the graph below will help you to identify a suitable tire size.
Bear in mind these are average conversions. You may be able to use wider tires, but make sure to account for tire clearance.
Without sufficient tire clearance you run the risk of a blowout or causing an accident if your tire is rubbing against or sits too close to your forks.
Additionally, remember that the table below only applies to 700c (622 ISO) wheels.
Internal Rim Width (Bead Seat Width) to Tire Width Chart (700c)
| Internal Rim Width | Tire Size Compatibility |
|---|---|
| 13-15, 17-19mm | 23 - 25c |
| 13-15, 17-19, 20-21, 22-23mm | 25 - 28c |
| 17-19, 20-21, 22-23, 24-25mm | 30 - 33c |
| 17-19, 20-21, 22-23, 24-25mm | 33 - 35c |
| 20-21, 22-23, 24-25mm | 38 - 40c |
| 20-21, 22-23, 24-25mm | 40 - 43c |
| 22-23, 24-25mm | 43 - 45c |
| 22-23, 24-25mm | 45 - 48c |
| 24-25mm | 48 - 50c |
Bicycle Tire Width - How Wide a Tire Can I Run?
So you’ve measured your wheel’s bead seat width and used the tire width chart above to determine which tire size you need.
But now you’re wondering how wide you can push your tire size without causing any issues.
Despite what we used to think about the thinnest, highest-pressure tires being the fastest option, research now shows that this isn’t the case [1].
With this better understanding of tire sizes, wider tires are now commonly found on road bikes.
So, it’s understandable if you want to increase your tire width. But just how wide can you safely go?
To measure and determine your maximum tire width, you’ll want to get hold of a set of callipers.
If you don’t have a pair, we advise you get some as they’re a super handy tool for bicycle maintenance and DIY.
- First up, you’ll need to take your callipers and measure your current tire width, at its widest point, and without pinching the tire. Make a note of this measurement.
- Next, you’ll want to check the current clearance you have around your tire in several positions.
Inspect the positions on your bike, labelled below, and any further areas of your bike where your tires are close to your frame.
- Seat tube
- Chainstays
- Seatstays
- Top of fork (crown)
- Mudguards (fenders)
- Pannier racks
For a road bike, you’ll want no less than 3-4mm of clearance.
For mountain and gravel bikes you’ll want to keep 5-6mm of clearance at a minimum.
5-6mm of clearance will allow your wheels to cope if you’re riding in muddy conditions or over other debris that may get picked up whilst riding.
If you know you’ll be riding in really rough/muddy conditions, you may choose to adjust your tire size, as bigger stones/twigs that are picked up on your muddy wheels can cause substantial damage to your bike if there isn’t enough wheel clearance.
Once you’ve located the area with the least clearance, use your callipers to measure this distance.
Next, follow this formula to calculate your maximum tire width:
Maximum tire width = 2 x (smallest area of clearance – desired minimal clearance) + current tire width.
So, for example, on our fixed-gear bike, the smallest area of clearance is 7mm. So, 2 x (7 – 4) + 25 = 31mm.
So, if we wanted to run tires with a 31mm width, we’d still have a minimum of 4mm clearance on either side of the tire.
One element that you’ll need to bear in mind with this calculation provides the height of your tires.
Low-quality tires can sometimes be taller in the middle than on the outside of the tire, whereas upmarket tires tend to have a consistent height across the whole tire.
Conclusion - 700c to Inches
So there you have it!
This guide covers and explains what 700c to inches is in plenty of detail, so we hope it helped.
If you didn’t already know the tire size you required, you should now also understand what tires you need for your wheels and the maximum tire width that’s safe for your bike.
If you manage to miss it whilst reading this short article, 700c to inches = 27.5″.
We always strive to improve the quality of the content we produce.
If you think there’s something we missed from this article, let us know in the comments section below, and we’ll add it to the article for the next reader to benefit from!
Recent Updates:
- 8th Dec 2023: We audited this review and updated elements to improve mobile usability.
- 10th Jan 2024: We refreshed content within the article to improve the quality of the information and ensure that the content is as helpful as it can be.
2 Responses
The information is simple and easy to understand. I have to replace a front tire on a Specialized Cross Trail.
Thanks for your feedback Ken, did you manage to find the right tire size?