(Last updated on March 6th, 2023)
I have several bikes, and they all have different wheel sizes.
Of course, I have wider tires for rough terrain and skinnier tires for paved roads, but what about the actual wheel size?
With three different wheel sizes and four bikes, each has its own separate sizing. Bike wheel sizes can seem unnecessarily complicated and confusing.
Moreover, you can always leave this stuff up to your local bike shop. But if you wonder, what bike wheel size do I need? You’ve come to the right place.
In this article, I will discuss standard bike wheel sizes. I’ll also review the typical tire widths for each size so you know what to look for when you put new wheels on your bike. But first, let’s take a quick look at what makes up a bike wheel. Let’s get started.
Bike Wheels
You might argue that the bike wheel is the most important part of the bike since it is your contact point with the ground. The combination of tire and wheel makes your bike feel comfortable and gives you a grip. But you might be surprised by the specific makeup of your wheel.
- Bike Wheel. The wheel is the common term that covers the rim, the spokes, the hub, and the tire. Sometimes, though, when you say bike wheel, it only refers to the rim and not the rest.
- Bike rim. This is the wheel’s hard circle with spokes and the hub attached to it. It’s the part that holds the tire in place. The rim is generally made of aluminum or carbon.
- Bike tire. The tire is the part that often confuses people. The tire is just the rubber part that fits onto the rim. Tires are available in multiple widths for your rim.
- Hub. The wheel’s hub is the part that attaches the wheel to the bike and allows it to spin.
- Spokes. The spokes connect the hub to the rim and give the wheel extra strength.
The size of your wheel is dependent on the type of bike that you ride. However, sizing labels on bike wheels aren’t always consistent.
Bike Wheel Sizing
You can almost always find the rim size written on the side of the rim. It will give you both the circumference (the large number) and the rim’s inner width.
Likewise, on your tire’s sidewall, you’ll find the intended rim size and the tire’s width. So to determine what size tires you need for your rim, just ensure these numbers match.
Bike Rim Sizing
Most road bikes use a 700C wheel. This designation is a throwback to an old French system using millimetres that isn’t in use anymore.
Only the name stuck.
The C is related to how wide the rim is, although we no longer use that designation.
Mountain bike wheels are sized in inches. The most common sizes are 26, 27.5, and 29. But don’t be fooled – a 29-inch wheel is basically the same as a 700C wheel with a wider rim.
Other bikes, such as cruiser, fat, and Brompton, also use inches to designate their wheel size.
ISO Bike Wheel Sizing
The International Organization for Standardization developed a universal system for rim and tire sizing to make things a little easier to understand. It was originally known as the ETRTO system because the European Tyre and Rim Technical Organization developed it.
The ISO numbering system is in two parts. The first number is the width of the inflated tire in millimetres. The second number is the diameter of the rim at the bead seat.
The ISO system helps you match the correct rims with the correct tire width. Generally speaking, the tire width should be anywhere from 1.45 to 2 times the inner rim width.
The chart below shows how the ISO number makes it a little simpler to understand.
Bike Wheel Sizing Chart
| Bike Type | Typical Wheel Size | ISO Size | Typical Tire Width in MM |
| Road Bike | 700C | 622 | 23 25 28 |
| Gravel Bike | 650B 700C | 584 622 | 28mm – 42mm |
| Mountain Bike | 26in 27.5 inch 29 inch | 559 584 | 2.0 – 3.25 inches |
| Hybrid Bike | 700c | 622 | 28-50mm |
| Cruiser Bike | 26 inch | 559 | 1.75inches – 1.125 inches |
| Fat Bike | 26 inch 27.5 inch | 559 584 | 3.8 – 5 inch |
| Brompton | 16 inch | 305 | 35 mm |
| BMX | 20 inch | 406 |
Road Bike Wheels
For example, if you ride a road bike, you will most likely have 700c wheels. Older road bikes tend to have skinnier tires – say 23mm, while more modern road bikes have wider tires, from 25 to 28. The ISO sizing for a 700C wheel is 622mm.
The width of your road bike wheels is determined in part by the rim width and your bike’s frame. Some road bikes can only fit tires as wide as 28mm, either due to the frame’s size or the brakes’ capacity if they are rim brakes.
Some small women’s bikes will have 650C tires (ISO 584). These are smaller rims that will reduce the overall height of the bike.
Gravel Bike Wheels
Gravel bikes will commonly have 700C (ISO 622) or even 650B (ISO 584) wheels. However, the tires that fit on these rims are usually wider to give you more grip on gravel or dirt roads.
In addition, gravel bikes typically have wider frames and disc brakes, which can accommodate wider tires. Many gravel bikes can fit tires as wide as 45mm, depending on the bike.
Mountain Bikes
Mountain bikes need to be able to accommodate even wider tires. So even though you’ll find the same rim sizes, the width of the rim will be wider, so the wider tires fit better.
So if you ride a mountain bike, you’ll find that the rims are measured in inches (the American standard), but you may want to convert that to the ISO standard.
It should be noted that a 29-inch mountain bike rim is technically the same size as a 700C road bike rim. But the tires are not interchangeable because mountain bike tires are much wider than road tires.
Your mountain bike wheels will be available 26in rims, such as on the Nishiki Pueblo, (ISO 559), or 27.5-inch rims (ISO 584), and 29-inch rims (ISO 622) like you would find on the Cannondale Trail 6. Regardless of the rim size, the width of a mountain bike tire will run anywhere from 2.0 to 3.25 inches wide and occasionally even wider.
Hybrid Bikes
Hybrid bikes vary a bit, combining the best of all the biking disciplines. However, they tend to be big, cushy bikes with upright flat bars and wide tires. You can use them for commuting, easy trails, or whatever you like.
A hybrid bike will have a 700c rim (ISO 622), but the tire width will vary from 28 to 50mm. The wider the tire, the slower but more comfortable your ride.
Cruiser Bike
Cruiser bikes are comfortable recreation bikes – the kind you might rent at the beach to ride on the boardwalk, for example. They have smaller rims and widish-type tires to make the bumpy ride more comfortable.
So a cruiser bike generally has 26-inch rims (ISO 559) and 1.75 to 1.125-inch wide tires.
Fat Bikes
A fat bike is an extreme mountain or gravel bike. A fat bike will have smaller rims – either 26 inches (ISO 559) or 27.5 inches (ISO 584), but the inner rim width will be wider to fit tires from 3 to 5 inches wide.
These extra-wide tires are meant to be able to handle very rough terrain, sand, and snow. But, unfortunately, the wider tires of a fat bike probably won’t fit on your mountain bike rims.
Bromptons
Bromptons are becoming increasingly popular as they are small, folding bikes that don’t take up much space. This makes them great bikes for commuting or storing in small spaces.
They have small 16-inch wheels (ISO 305) like you might find on a children’s bike. However, the width is usually around 35mm, so they’ll be comfortable.
BMX Bikes
BMX bikes are smaller bikes made for tricks. The wheels are usually only 20 inches (ISO 406), but they can hold 2.3 to 2.4-inch wide tires, so you get plenty of grip for the small tire.
Vintage Bikes and Other Types of Bikes
ISO sizing is helpful because plenty of bikes don’t fit the typical sizes. For example, vintage bikes, bikes from other countries, and children’s bikes may all have different sizing. Kids’ dirt bikes will be different, as well. In addition, you can often look up the correct size from the manufacturer if you need help figuring it out.
Final Thoughts and Real-Life Examples
As you can see, there is always some overlap between wheel sizes and tire sizes between the different riding disciplines. You can watch a little bit more about tire sizes in this Park Tool Video.
But here’s a real-world example for you to see how to put all these different sizes into action.
I have an XXXS Women’s Canyon Ultimate road bike. It uses 650c rims and 25mm tires. My Quintana Roo is a little bigger and uses 700C wheels with 25mm tires. Unfortunately, the Quintana Roo wheels won’t fit on the Canyon.
On the other hand, I have a LIV Brava with 700C wheels and 42mm wide tires. I can (and have) put the Quintana Roo tires on the LIV when I need to ride it on pavement, but the LIV wheels are too wide for the Quintana Roo.
My Jamis Renegade uses 650B wheels with 38mm tires to make it more complicated. These wheels won’t fit on my Canyon or my Quintana Roo, but I could put them on the LIV if I wanted to.
Although it all sounds complicated, it makes a lot more sense when you stop and consider how big or small the rim is and how wide the tire is.
Your bike’s intended terrain use, frame size, and brake type are the major factors in determining what size bike wheel you need. Remember to check the size of your bike rim and bike tire for what size you have on your bike.
Frequently Asked Questions
You probably cannot put a mountain bike wheel on a road bike because the rim will be too wide. Mountain bikes have wider rims because they need wider tires to manage the terrain.
Generally speaking, yes.
As long as the rim size is the same (typically a 700c), your gravel bike should be able to accommodate road bike tires. Many people do this so they only have to have one bike.
If you have disc brakes, you might be able to swap out your 700c wheels with 650c wheels. This could give you enough room in your bike frame for slightly wider tires.
Early on, each country had its own method for sizing wheels. Now that our world – and the bike industry – has become more global, the need for consistent sizing has become more apparent. The ISO numbers are the most consistent type of sizing we currently have.
You might be able to put a mountain bike tire on a road bike wheel, but probably not.
Mountain bike tires are much wider than road bike tires, so even though the rim is the same diameter on both types, the width of the rim is much wider on a mountain bike wheel.
Therefore, if you try to fit the tire onto the road bike rim, it might not seal properly or mushroom too much and give you pinch flats.
Amanda Whittington is an expert writer, impassioned cyclist, and musician. Coming from a diverse educational background, Amanda discovered a deep-rooted passion for encouraging others through her love of all things cycling, writing, and inspiring hope.
You’ll likely find Amanda pouring over bike specs, comparing the hottest cycling tech, and sporting the latest jerseys while juggling the demands of her editorial calendar, training schedule, tiny homestead, and 6 busy kids.
She spends her free time absorbed in her own gardening and fitness, cycling, and reading, all while encouraging adoption and foster care, championing the underdog, and of course, working with her chickens and goats.
