The Definitive Guide to Mountain Bike Tire Sizes

Choosing the ideal mountain bike tire size isnʼt as easy as you think. Since there are a plethora of options on the market, and with each mountain bike tire brand claiming to be better than the next, selecting new tires can be quite arduous. 

Lucky for you, Iʼm here to help you through the process.  

There are a few important factors to consider before splurging on a new set of mountain bike race tires. Weʼll go through some important ones (including mountain bike tire size) to help you take your mountain bike experience to the next level.  

When considering mountain bike tires (especially bike tyre size), you need to take into consideration the places youʼre likely to ride the most, your riding style, and the type of bike you own. These factors will ultimately determine the specific tire width, rolling resistance, diameter, and tread pattern you should go for.

Without beating about the bush any further, letʼs go through some bike tire specifications you must learn in order to select the correct set of mountain bike tires. 

Tire Wheel Diameter

Most tires for mountain bikes on the market today are offered in one of three diameter options (wheel size): 26, 27.5, and 29 inches. Out of the lot, the 26-inch variety is the most commonly used tire. 

These are good for freeride, kids’ bikes, and dirt jump.

When selecting a bike tire diameter, you should consider the frame of your bike. You see, every bike frame has been designed with a specific tire size in mind. 

So, if you try to install 29-inch tires on a bike that has been engineered to accommodate 26-inch tires, you may face difficulties handling, controlling, and maneuvering your bike.  

In a nutshell, if your bike is a 26-incher, you should upgrade your entire bike to accommodate fat tires, instead of forcing 29-inch wheels on it.

Selecting mountain bike tires according to diameter 

The thing is, all three diameter options come with their fair share of advantages and disadvantages. Thatʼs why it is essential that you factor in the places youʼre likely to ride the most and your riding style when choosing the right tire diameter.

Most mountain bikes with 26-inch bike tires are considerably more nimble than their larger counterparts. Additionally, they facilitate faster acceleration. 

Unfortunately, they arenʼt perfect as they tend to have higher rolling resistance. As a result of this increased rolling resistance, they arenʼt the best choice for riders who go over obstacles frequently on their rides.

Riders who prefer aggressive trail riding on tracks with rocks, logs, and huge obstacles should opt for 29-inch tires. 

Larger tires as such maintain better momentum and are therefore able to roll over larger obstacles with minimum fuss. Of course, 29-inch tires arenʼt perfect either as they can be a pain to maneuver.

Thatʼs why riders looking for the best of both worlds tend to go for the middle option—27.5-inch tires. Though 27.5-inch tires arenʼt the best in any specific department, they are considered the most reliable and practical choice by many.  

Mountain bike tires’ width

Selecting the right bike tire width is also of paramount importance when looking to elevate your mountain biking experience.

Most mountain bikers usually go for mountain bike tires with tire widths of 1.6 inches to 2.6 inches. You can measure the width of the tire from one edge to another at the start of the tread.

Of course, thereʼs a good reason some people opt for a 1.6-inch width over 2.6 inches. You see, thinner tires on smaller wheels are engineered to create less rolling resistance with the ground, ensuring they have more rolling efficiency. 

In essence, the low rolling resistance makes them ideal for long-distance riding. And, since they are made with less material because of their narrower widths, they have a lighter weight than their wider counterparts. 

However, since they have less surface area, they donʼt have much puncture resistance. And they don’t offer as much grip as wider tires either. 

Additionally, external factors such as snow and sand can also negatively affect the performance of thinner tires.

On the other hand, large tires are capable of creating more friction with the ground, owing to their larger overall air volume. This allows them to offer more grip on the road, making them ideal for slippery and loose conditions. 

Additionally, a wider tire is also better at rolling over obstacles, owing to its larger surface area. Its larger surface area also facilitates better overall braking of the bike.

Unfortunately, their width, increased grip, and larger size can also be disadvantageous in certain areas. For instance, they have slower rolling capacity and require more effort to pedal because of their heavier weight.

Wider tires are generally preferred by aggressive riders who prefer their tires to be more puncture-resistant.

Let me make things easier for you to follow. If you are into cross-country riding, go for a set of tires with a tire width ranging from 1.9 to 2.3 inches. Enduro and downhill riders should go for a tire with a tire width ranging from 2.3 to 2.6 inches. 

If you are an all-mountain rider, tires with a 2.5- to 2.6-inch width would serve you best.

Plus and Fat Road Bikes

Of course, there are wider models for the more daring, adventurous riders. These models are labeled as plus and fat-bike tires. 

While plus tires have a tire width range of 2.6 to 3.2 inches, fat-bike tires can operate in the 4- to 5-inch range.

If you’re new to the fat-tire scene, I’d recommend plus tires as they are far more forgiving and user-friendly. They are better than fat-bike tires at rolling over obstacles and going downhill. 

Fat bikes are generally used for specific situations, such as cycling on ice and sand. In such conditions, fat bikes tend to float across the top instead of digging in.

As I mentioned earlier, bear in mind that plus-sized tires and fat-bike tires arenʼt compatible with every bike frame. If your bike’s frame and fork donʼt have proper width clearance, the fatter tires wonʼt be able to roll out smoothly.

If your riding situation demands the use of plus-sized and fat-bike tires, youʼre better off investing in a plus-sized or fat bike. Retrofitting your current bike forcefully to accommodate larger tires would be a wasteful effort.

Mountain Bike Tire Tread

Next, letʼs look at bike tire treads. 

Tread plays a pivotal role in determining the type of tire you need for your riding adventures. The tire tread on a bike largely affects a tire’s rolling resistance, and how it grips and stops.

When looking at the tread on a bike, you need to pay attention to its knobs, which come in all shapes, heights, and sizes.

Shorter, smaller knobs are excellent for hard-packed surfaces as they offer superior grip without decreasing acceleration. However, they donʼt provide the best braking power. 

Meanwhile, medium-sized knobs offer similar benefits and then some; they offer better bite for softer terrain. 

Last but not least, we have large knobs. Large knobs are the best on downhill rides and rides on slick surfaces and loose trails as they provide better traction.

Additionally, it’s important to focus on the tread pattern of tires. Tires designed for cross-country tend to have tighter tread patterns with smaller knobs. 

On the other hand, tires marketed for downhill bikes tend to have larger knobs with wider spacing between the knobs. The larger spacing offers more grip and makes it easier for the tire to shed loose material like mud during rides.  

Tubed or Tubeless Tires for Mountain Biking?

I think we have a clear winner here. As a mountain biker, I think itʼs best to go for tubeless tires. 

When you ride in the mountains, you ride on harsh surfaces full of sharp objects such as rocks and gravel. So, it doesnʼt make sense for you to use tubed tires on such rides, unless you’re itching to experience “pinch flats” or “puncture flats.” 

With tubeless tires, you’d only need a tubeless sealant to fill the small punctures. Plus, they can operate on lower tire pressure and, therefore, offer more traction for a more comfortable ride. 

Sure enough, such tires tend to be more expensive and difficult to install, but they offer peace of mind – no one wants to be stranded in the middle of nowhere.

Additionally, you can also look at the tire bead to select a tire more suited to your riding technique. 

In this department, you usually have two options to choose from: wire bead or Kevlar (a heat-resistant synthetic fiber). Kevlar is the lighter option but it does cost more. 

Most brands spend a lot of time researching the best rubber compounds for bike tires to find ones that allow for excellent grip, durability, and low rolling resistance. 

It can get quite complicated when you start to look into the different rubber compounds used in bike tires. However, all you really need to know is that soft tire compounds have more grip but wear out quicker, and firm tire compounds have less grip but last longer.

Conclusion

Ultimately, mountain biking can be a dangerous sport if you and your bike aren’t properly equipped. So, having the correct tires is important if you want to stay safe. 

Hopefully, these tips have equipped you with the information you need to select the ideal mountain bike tires without having to seek professional help.