So you’ve got a pair of 700c wheels and are trying to figure out which tires and inner tubes you need. You’ve come to the right place.
In this short guide, I’ll explain and talk you through how you can convert 700c to inches. Of course, it’s also essential to figure out what width you need so that you buy the right size tires and inner tubes!
Towards the middle of the article, I include a 700c tire size chart, where you’ll find a few different recommendations of some durable, good-value brands.
If you don’t yet know what size wheels you have, check out this simple step-by-step guide, which explains how to measure a bike wheel for tire and tube sizing.
As always, I promise not to bore you anymore than necessary, so let’s get stuck into it!
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 obviously, the 700c wheels you’d find on a road bike are drastically different from what you’d expect on a hybrid, so why are they called 700c wheels, you ask?
To be honest, this name is almost redundant now since there are so many different 700c wheels and tires available.
The “700” part 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.
The “c” comes from old French Tire sizing and has remained on bike wheels, despite not meaning anything anymore. The lettering ranged from A to D and referred to the tire’s width, but this 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 all 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 find a reading along the lines of “45 – 622”.
Below is a quickfire table on the rough widths you can expect to see on different 700c bike tire types, first as you’ll find in millimetres and then translated to inches.
Towards the end of this short guide, you’ll find a more accurate wheel/tire size chart.
| 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, let’s find out about 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 simply bought a random set of 27.5″ tires, they probably wouldn’t fit your bike as wider tires require more clearance.
So, 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 likely chafe against your frame.
For those who want an accurate tire size 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, follow this simple 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 my 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 as 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 measure your wheels bead seat width an 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, and rightly so.
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].
Now that the facts are understood, wider tires are being found on road bikes, so I understand 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, I 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. This will allow your wheels to cope if you’re riding in muddy conditions or with small rocks that might 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 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 my fixed gear bike, the smallest area of clearance is 7mm. So, 2 x (7 – 4) + 25 = 31mm.
So if I wanted to run tires with a 31mm width, I’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 is the height of your tires. Cheaper 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.
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″.
I always strive to improve the quality of the content I produce. If you think there’s something I missed from this article, let me know in the comments section below and I’ll add it to the article for the next reader to benefit from!
Otherwise, if you have any questions let me know below and I’ll get back to your right away.
As always, lock it or lose it.
Ciao for now.
Sources
[1] Thinner tires are not faster – Conti-Tires
[2] What width tires can you use – RenéHerse
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?