Road Bike

How Big Are Road Bike Tires?

By: Alex Bristol

Last Update:

How Big Are Road Bike Tires?

When was the last time you replaced your toothbrush? I don’t remember either, but have you noticed how new toothbrushes get soft and lose their strength eventually?

The same thing happens with tires. Well, kind of.

After a while, bike tires get worn out and lose their grip, especially if you’re like me and go everywhere on your bike, so they just don’t work the same as they used to.

So, just as your toothbrush needs replacing regularly, you need to do the same with your road bike tires. When the time comes to change my bike tires, I like to shop around and consider other tires that may have different characteristics that suit my needs.

To do this though, you need to know how big are your road bike tires? Which type of tire should you use? and how do you know when it’s time to change them?

In a nutshell, a road bike tire is usually 700mm in diameter and 25mm in width on average. Tire size and widths vary with the type of bike so there is a selection of different tires to fit your needs on a road bike.

In truth, there are many options on the market for tires, so you need to know exactly what you’re looking for and what would fit your current bike.

When To Change Your Tires

The general saying is that you should swap out your tires after around 1,000-3,000 miles of cycling or more if they’re high-end.

But who keeps track of how many miles they’ve cycled anyway? I always forget, luckily there are a few tell-tale signs on your bike that may mean it’s time to change those tires.

If your bike has wear indicators, usually one or two dimples on the tire, this will be easy as all you have to do is see if they’re still deep dimples or if they’ve become smooth.

You may be able to notice some general damage, such as small cuts or slivers of glass accumulated over time or if you’re getting flat tires often. You may also see rubber cracks or flakes off knobs/sidewalls.

Another indication could be an uneven or round tire tread, or a tread pattern starts appearing on the tire sidewall. Some tires have small slits called siping and this can disappear in worn tires.

In tires that are more worn, you might get a sense that the bike handling is significantly worse, or even that there is some distortion in the tire from damaged casing under the outer wall.

It’s a good idea to check your tires regularly for any of these signs so that as soon as they come up you can get a fresh set of tires in.

How To Tell What Size Bike Tire You Have

Some things about bikes can be pretty complicated, but finding out what size your tires are isn’t one of them. All you have to do is check your tire’s sidewall.

There you will find numbers indicating the tire width and diameter, for example, 700x32c

This would indicate a tire width of 32mm with an outer diameter of 700mm. The “c” is a category of bike sizes, from “a”, “b”, and”c”.

Sometimes you might find more than one set of numbers on the sidewall, as long as your new tires match one set, your tires will fit.

Sizing will different for a mountain bike tire and on a road bike tire. For example, you may see something like this:

Mountain bike tire: 27.5 x 2.3 which would be 27.5″ outer diameter with 2.3″ width

Road bike tire: 700 x 25c which would be 700mm outer diameter and 25mm width

You may also come across ISO numbers written as 25-622 which would be the same as a 700 x 25c, but the made diameter is smaller to ensure the wheel size and inner tire fit together. However, there are usually other measurements included on the tire.

Choosing The Right Bike Tire Width

If you’re looking to replace a tire, you need to use the right dimensions, especially the diameter of the tire so it fits your wheels.

You may have a little room to play around with your preferences in width, but double-check with the bike shop to ensure the new tire is still compatible with your bike.

Fat or Plus tires are usually 4″ or more, but you can get mini variations at 3″. They are used for cycling on snow or sand and offer more grip and a comfier ride.

Mountain bike sizes include 26″, 27.5″, or 29″ on the outer diameter. Width varies from

Road bike sizes include: 700mm outer diameter with widths of 23mm all the way to 45mm, the thicker widths are used for gravel roads. Most road bikes require 30mm width

Kids’ bikes will usually range from 20″ to 24″ with a good variety of widths. Getting wider widths is great if you’re looking for increased grip out on the road, or if you want something faster a slimmer tire can do the trick, so find out on your next trip to the bike shop what your tire options are.

Other Bike Tire Choices

Now that you understand sizing, you may be wanting to upgrade your current tires. What are some of your options?

Clincher: Clincher tires are the most commonly used road bike tires. These tires have a tube that is placed between the rim of the wheel and the tire. This tube inflates to hold air and can be easily replaced or fixed in the case of a puncture. They also have wire and a folding which fastens beneath the rim to hold the tire in place.

Tubular: Tubular tires are quite popular with professional riders. The tire sticks to the rim. This is great in case of a flat tire as well because now you can continue to ride your bike without losing control of it. Tubular tires have an inner tube sewn into the tire instead of being separately available. Changing a tubular tire is not as easy since you need another pre-glued tire for that. Keep in mind if you’re on a budget, these tires are quite expensive

Tubeless: Tubeless tires are for mountain bikers however people have started to use them as road bike tires too. These tires do not have any tube which creates a tighter seal than the clincher tires. These tubeless tires provide a smooth ride and improved traction, so riders will feel more comfortable and have more control over their bike. Tubeless tires can also be used at low pressures. However, you do need the correct type of wheels to be able to use these tires.

Frequently Asked Questions

What size are road bike wheels?

Most road and racing bicycles today use 622 mm diameter (700C) rims, though 650C rims are popular with smaller riders and triathletes. The 650C size has an ISO diameter size of 571 mm.

Can you use different wheels on a road bike?

Except for the looks, there’s no disadvantage to riding different wheels on front and back. Pro-level riders on the grand tours will run different front and rear wheels depending on the stage. It’s widely accepted a good idea to have the front and rear wheels weigh a close to the same as possible.

Are lighter bike wheels faster?

Lightweight wheels accelerate faster than heavy ones, which helps when you’re taking off from a stop, but heavy wheels maintain more of their momentum than light wheels, which helps you keep your speed on rolling roads and trails.

Do road bike wheels make a difference?

Saving wheelset weight will make a huge difference to your sense of acceleration and overall energy efficiency and endurance while out riding. A wheelset upgrade allows you to access multiple performance advantages in a single purchase: better rotating efficiency, ride quality, and aerodynamics.


Road bike tires come in pretty standard sizing, as do mountain bikes. When looking for road bike tires, you need to ensure that the wheel of your bike is also compatible with the tire. This will ensure maximum efficiency and a smooth and comfortable ride.

Once you can read and understand tire sizing, you can play around with the options available to select tires with the right grip, cushion, and speed for you.

We’ve covered everything you need to know about road bike tires here but if you still want some extra info then check out our other article on which road bike tires to buy here.

Now you’re a fully-fledged expert on how big road bike tires are you can go forth and have some extra knowledge on your belt when looking for road bike tires.

So go forth and have fun pedaling!

Latest guides

Best Hybrid Bikes

Bikes, Electric Bikes, Hybrid Bikes

Best BMX Pegs

Accessories, Bikes, BMX, Components, Parts

Best Road Bike Computer

Accessories, Technology

Best Budget Bike Computer

Accessories, Technology

Leave a Comment