Everything You Need To Know About Bike Tires and Why It Matters

Beads

Tires are held into place on the rim by beads, which grip it when the tire is inflated. The most basic versions found on more affordable tires are wire beads made of steel. The more you spend on a tire, the better and more advanced the beads will be, made from synthetic materials such as Kevlar.

Flexible beads, also known as “Kevlar beads,” are found on folding tires. What makes them foldable is the fact that the beads can be easily bent –by comparison, wire beads can only be partially folded. Kevlar beads are lighter and make installing and removing tires easier.

Casing

The casing (or carcass) is the fabric that forms the basic structure of the tire. A tire’s feel and handleability are affected by the casing’s material, design, and number of threads per inch (TPI).

Generally, the higher the thread count, the more flexible a tire will feel, which leads to better handling, control, and overall ride quality. Of course, it also means an increased cost. What’s more, some tires come with reinforced sidewalls for more protection against punctures.

Tread

Next, we have the part that meets the road or surface you’re riding on: the tread. There are two important factors here: the amount of tread and the pattern of the tread.

More tread means additional weight, but also increased wear. The ride quality is better with less tread, but you sacrifice some durability. Road tread also differed in hardness – harder rubbers last longer, while softer compounds offer better grip in corners.

Depending on your needs, you can choose the ideal balance. There are also tires with dual-compound tread designed to provide excellent traction and good wear and even tires with tread made specifically for wet roads.

If you ride off the beaten path, it’s important to choose tires with suitable tread, as it will significantly affect your traction, control, and ride quality. Manufacturers design treads for specific types of terrains and conditions – for instance, if you ride in the snow, you’ll find tires made specifically for that.

Sometimes, you’ll find something known as “directional tread” on mountain bike tires. It’s meant to provide top-of-the-line handling, traction, and control through rear- and front-specific designs. Directional tires have markings that indicate which wheel they belong on and which direction you should mount the tread.

Sub-Tread

You’ll find tread on every tire, but not all tires have sub-treads. Sub-treads typically appear on tires with additional puncture protection. Manufacturers add an extra nylon or Kevlar layer to the tire to prevent sharp items from piercing the tube.

A tire with sub-treads costs a bit more, but it’s definitely worth the extra bucks, especially if you typically experience many flats. The only downside is the little added weight, which probably won’t affect you unless you’re a racer or all about setting fast riding times.

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Types of Tires by Construction

There are three main types of tires. The most common type is tires with tubes inside. The tube is made from rubber and comes with a valve, which you use to pump air inside it.

If you’re a bike rider, you’ve most likely experienced a flat tire at least once. Fixing it is simple with tubed tires—just remove the tire and replace or patch the tube to fix the problem.

Then, we have tubeless tires, which are similar in design to automotive tires in that they have no tube inside. How is that possible? The rim and tire seal the air inside. One advantage of tubeless tires is their ability to run lower pressures with a low risk of flatting, even on extreme terrains. Moreover, soft tires translate to a smoother ride and more control.

Riding on tubeless tires is also smoother because there’s no tube – you feel the tire directly. However, repairing a tubeless tire isn’t as simple as a tubed tire, as you need a special repair kit. That being said, tubeless tires are way less prone to punctures.

Finally, we have sew-up tires, also known as tubular tires. They’re the least common type, usually found on high-end road bikes, and are suitable mainly for racing. What’s more, they have a round tubular profile, hence their name, and are sewn together at the tube’s belly, giving them a round profile.

The upside of a round profile is a supple ride that absorbs much of the shock involved with riding. Furthermore, tubular tires and rims weigh less than conventional tires, offer better acceleration, sprinting, and climbing, and will even corner better than other racing tires.

As expected, fixing a flat on a tubular tire is a bit more difficult. You must cut the tire’s threads, remove the tube, patch the hole, and then sew it up again. Tubulars need a special rim with a flat surface on top, as the tires are glued to the rims during installation. It’s safe to say that most riders, especially on the road, won’t spend time fixing it. They will peel off the bad tire and install the spare.

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Sizing

Now that you know the types of tires, let’s move on to another critical aspect: sizing. Finding out what tire size you need is as simple as looking on your tire’s side, where you’ll find a tire label or a size marking. Some of the most common sizes are 700 x 25c, 26 x 2.0, and 27 x 1 ¼.

But what do these numbers actually mean? Well, the first number refers to the tire and wheel diameter – for example, “26 or “27” represent the tire and wheel diameter measures in inches, while “700” represents the same thing but in millimeters.

The second number, such as “2.0, “1 ¼,” and “25c,” refer to the tire’s width – again, it can be either in inches (2.0) or in millimeters (25mm). Oh, by the way, the road bike tire designation “c” is just a French tire size – it does not stand for a numerical measurement.

Things get even more complex, as you might also find an ETRTO (European Tire and Rim Technical Organisation) sizing usually printed on the sidewalls of tires, controlled by an ISO international standard. The ETRTO number is expressed in millimeters.

For example, a 700c or 29-inch wheel and tire will have an ETRTO diameter of 622mm, while a 650b or a 27.5-inch wheel will have an ETRTO diameter of 584 mm. Long story short, the wheel/tire diameter is combined with the tire width to create the full ETRTO number.

Next, it’s almost needless to say that you need to match diameters when shopping for tires. If you have 29-inch wheels, you’ll need 29-inch tires. Changing widths is more flexible. The tire’s width will affect comfort, traction, and ride quality.

If you switch from a 26 x 1.5 tire to a wider, 2.0 one, you’ll have more comfort and handleability because the tire has more surface and air. On the other hand, downsizing will save a little weight, and a narrower tire translates to faster acceleration.

Remember that not all bike frames and rims are compatible with all tire widths. Going up or down one or two widths generally works, but if you want to make a bigger jump, you’ll need to do some research and see if it’ll be a good fit.

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Most Common Tire Sizes

Let me run through the most common tire sizes. The 700c is the most common tire/wheel size for road bikes, but you’ll also find it on commuter and gravel bikes. 700c tires with narrow widths and smoother treads are ideal for speed on pavement. Increase the width and tread, and you’ll have better control over rougher surfaces.

The 29-inch tire/wheel size is the largest available for mountain bikes, offering faster top speeds and better rollover capability. However, shorter riders might find them a bit hard to control. They might be better riding on 27.5-inch tires, which are also a common MTB size that favors agility over top speed. Adult mountain bikes used to have 26-inch tires/wheels, but they’re not as popular nowadays.

Finally, 650b tires are usually found on touring and gravel bikes. They have the same inner diameter as 27.5-inch MTB tires but are more suitable for all-terrain adventure riding instead of trails.

Types of Tires by Bike

Road tires are all about making you go fast, long, and smooth. They have minimal tread to keep rolling resistance low. Most modern road bike tires are sized at 700c, and their width varies from 23mm to 32mm.

Gravel bikes typically have 700c wheels, but many manufacturers offer you the option of installing 650b wheels. The latter is a bit smaller, allowing you to fit wider tires for improved grip and comfort on rough roads. Moreover, the average width of gravel tires increased from 35mm to a new standard width of 40mm. If you plan on riding on really difficult terrain, you can go for 42mm or 45mm sizes.

Choosing the right tread is essential for gravel bike tires. A low-profile tread pattern performs well on fine gravel, dirt roads, and dry weather. Choose tires with heavy tread and a knobby texture if the conditions get tougher or muddier. The knobs on gravel tires are much smaller and closer together than the ones on MTB tires.

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Things get a bit more complex when discussing MTB tires. They range in width from 1.6″ to 3″ and are available in distinct tread patterns meant for different terrains. Generally speaking, the more technical the terrain, the better it is to have wider tires, as they provide more traction and shock absorption.

For example, cross-country racing tires need to roll fast, so they come with a low-profile pattern with knobs closer to one another. Then, trail, downhill, and enduro tires have larger individual knobs with more space between them to properly dig into the ground.

Tread patterns can differ in the center and edges of the tire. If the texture is smooth in the center, you can achieve more straight-line speed, while larger knobs on the edges can interlock with the ground for better grip.

You can also find studded MTB tires, which integrate small metal spikes into each knob. They’re designed to dig into snow or ice and are not suitable for riding on pavement as they can damage it.

The largest bike tires available are commonly known as fat tires. They range from 3.7″ to 5.2″ in width, with the most common width being 4″ across. The wider you go, the heavier and slower you’ll be, but you gain better traction. Furthermore, fat tires come in two diameters: 26″ and 27.5″

Replacing Tires

It’s essential to know when you should change your tires. There are two main reasons why riders change tires: they become worn-out and are no longer safe to be used, or the riders prefer new tires to change the bike’s handling and ride quality.

So, how can you tell when a tire is too worn? There are multiple signs, which I will detail below. A reliable one is that you keep getting flat tires. This happens because the tread becomes so thin that it can no longer protect the tube.

Instead of waiting for the flats to happen, you can inspect your tire visually before you start your ride. Check out the depth of the grooves in the tire – when they disappear, it’s time to get a new tire.

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If you ignore the wear and keep on riding, you’ll eventually expose the casing threads underneath the tread. This is a crystal clear sign that you should replace the tire as soon as possible.

Another sign you might encounter is the tire squaring off. This happens to rear road tires at the tread’s top part, which flattens after many miles. This phenomenon makes the tires slower and indicates you should replace them soon.

Time takes a toll on tires. If you store a bike for a longer time, you might find that the rubber hardens and cracks. What’s more, the sidewall can crack and rot. In the latter case, you shouldn’t risk riding on those tires – even if they hold air, they might give out unexpectedly, which can lead to a crash.

Finally, if you know how fresh tires fell, you might be able to tell the tires need replacements based on how they ride. For instance, worn-down mountain bike tires will offer less traction.

Tire Pressure

All tires are printed with the manufacturer’s recommended pressure gauge. The science of tire pressure can be a bit complicated, but here’s what you need to know. Generally, the larger the tire and the rougher the surface, the lower the optimal pressure is. Moreover, tubeless tires can be ridden at lower pressures than tube tires of the same size.

Wider tires require less pressure for the same air volume than narrower tires. Moreover, wider tires at lower pressures reduce bouncing and are faster on most surfaces than smaller and harder tires.

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There isn’t any generalized recommendation for pressure – it depends on your weight, the riding conditions, and tire type and size. Finding the right pressure becomes even more important when mountain biking, as even small changes in pressure can significantly impact handling and performance. You can find various calculators online that take into account the weight, conditions, and equipment – that’s a good starting point for discovering the tire pressure that best suits your needs and riding style.

I hope this guide has helped you find the right tires for your bike, or at least made you more familiar with bicycle tires. Let me know if I missed any critical info in the comment section below. Happy riding!