MTB Rubber Compound Overview (2022 Technology)
Contrary to popular belief, it’s not so much the visible tire tread but the rubber compounds that determine what is perceived as traction on the trail. Tire compounds are what the actual tread pattern is made out of. Every rubber compound consists of natural and synthetic rubbers among other ingredients. The quality of the materials used has a significant effect on the characteristics of the rubber compound and thus the performance on the trail, even though it’s just one part of the entire modern bike tire design.
Four properties, in particular, are very important in a modern mountain bike tire compound:
- Grip
- rolling resistance
- damping
- durability
Ideally, a tire should provide a lot of grip, have low rolling resistance, offer maximum damping and also be very durable and long-lasting. In reality, however, these demands are contradictory: a very soft tire with high damping always suffers from higher abrasion. Similarly, a tire with a lot of grip will never excel with the lowest rolling resistance. So, a single compound can never provide the answer to everything.
Instead, rubber compounds are always about finding the ideal compromise for a particular riding style.
The best MTB tire compounds
Tire compounds are a complicated topic and heavily depend on the intended riding style and conditions. This is why there can never be one ultimate tire compound. But tires are designed and built for very specific purposes. Finding what tire compound fits your riding best can be overwhelming. Even reading the sidewall of your tire is a puzzle. Which is a shame, because the compound selection is among the most important decisions on a bike tire.
In the following table, every tire compound made in 2022 by the major bike tire manufacturers is listed. These are the recommended mountain bike tire compounds for your riding discipline:
| Tire Brand | Rubber Compound | Number of Compounds | Cross Country | All Mountain | Enduro | Downhill |
|---|---|---|---|---|---|---|
| Maxxis | MPC | Single Compound | XC | AM | ||
| Maxxis | MaxxPro | Single Compound | AM | EN | DH | |
| Maxxis | Exception | Dual Compound | XC | |||
| Maxxis | SuperTacky | Dual Compound | DH | |||
| Maxxis | Maxx Speed 3C | Triple Compound | XC | AM | EN | |
| Maxxis | Maxx Terra 3C | Triple Compound | EN | |||
| Maxxis | Maxx Grip 3C | Triple Compound | DH | |||
| Schwalbe | Addix Speed | Dual Compound* | XC | |||
| Schwalbe | Addix Speedgrip | Dual Compound* | XC | AM | ||
| Schwalbe | Addix Soft | Dual Compound* | AM | EN | DH | |
| Schwalbe | Addix Ultrasoft | Dual Compound* | EN | DH | ||
| Continental | Pure Grip | Dual Compound | XC | AM | ||
| Continental | Black Chili | Dual Compound | XC | AM | EN | DH |
| Onza | TRC 60 | Dual Compound | XC | AM | ||
| Onza | GRC 50 | Dual Compound | EN | DH | ||
| Michelin | GUM-X | Dual Compound | XC | AM | EN | |
| Michelin | Magi-X | Dual Compound | EN | DH | ||
| Vittoria | Graphene 2.0 | Quadruple Compound | XC | AM | EN |
* Assumption on my part as this information is undisclosed by Schwalbe, and likely no triple compound.
I hope this rubber compound overview is helpful to you or at least can help you steer in the right direction. Price can vary drastically between the options. And so do the actual tire treads and tire casings. Those are usually matched for combinations that make sense for particular riding to keep the options somewhat limited and relevant.
If any of that is new territory, or you want to know more about tire compounds, follow me down the rabbit hole. I guess I’ll start with the basics and build from there.
What is a tire compound?
A bike tire compound is the rubber material the tread pattern and sidewall are made of. Single, dual, and triple compounds are common for mountain bike tires, that need to perform in various conditions. Handling differences between rubber compounds are more pronounced the harder or wetter a surface is.
While the actual tread pattern of a tire is the only part of a bike actually touching the ground, how that tread pattern performs in various conditions depends on what rubber compound is used for it. Because of that, there are a lot of different compounds of rubber available.
This is why a rubber compound within the tread is arguably the most critical part of a tire. Two tires that are identical in tread patterns (this is the model name), casings, and size can perform drastically differently with two differing rubber formulas. Or even different compound layering.
By using rubber technologies, manufacturers can really fine-tune a tire’s behavior to the type of riding and riding conditions. And so can you as a rider. Two different compounds on one bike is in fact very common. Since there’s generally more weight on the rear wheel on a mountain bike due to body position, riders prefer to have a stiffer, durable and faster rolling tire in the rear.
Under braking, it’s the opposite, when weight shifts forward. Since the vast majority of actual braking performance comes from the front wheel, the grip in the rear is less important. The same goes for cornering. Front tire slip is hard to recover from, as opposed to rear-wheel sliding.
To benefit from the characteristics where you need them, it’s pretty common to use a softer rubber compound on the front tire and a firmer one in the rear. There is similar reasoning for tire width, where running a slightly narrower rear tire is a fairly common choice as well.
Shore durometer scales for bike tires
How firm a rubber tire compound is, is measured using the Shore durometer. It’s a standardized device for measuring the hardness of materials like polymers, elastomers, and rubbers. A higher number like 60a for example (seen on Onza’s labeling) is firmer and more durable, meaning it rolls faster but has less grip as a drawback.
You get the complete opposite with a lower number of 45a, namely much more grip due to more compliance of the rubber itself that allows it to conform around obstacles. That’s also what makes the tire roll much slower because a more conforming tire generates traction by increased resistance. Softer rubber is also going to wear out faster, not unlike an eraser that turns into rubber marbles by a piece of paper.
Please note, that I am not even talking about tread patterns here. These are just purely variations in the material a tread is made of.
For comparison, a gel bike saddle is between 15 and 30 Shore.
But unless you know what these Shore durometer numbers mean, it can get confusing to know which tire to go for. This is why manufacturers now have their own names for their compounds. Which can get equally confusing because everyone comes up with their own good-sounding marketing words like MaxxTerra, Addix Speedgrip, Gum-X or Black Chili. Only Onza puts at least one Shore number in their dual compound labels. It doesn’t help that between a Black Chili Cross Country tire and a Black Chili Downhill tire they don’t even have similar Shore values. Those names just indicate a range of firmness for a specific riding discipline.
What type of rubber is used in bicycle tires?
The rubber compounds of the tire tread and sidewalls are usually made from natural rubber, while synthetic rubbers, like butyl rubber, are used in the tire’s casing and puncture protection. This is because the tread pattern has to provide grip by conforming to the ground, while the casing provides stability and predictability for the entire tire.
That’s the basic gist of it. The tire casing attaches to the rim while the tread is in contact with the ground. They are two different parts of a tire responsible for doing to very different jobs. But let’s stick to the tread compounds. While natural rubber generally has properties you’d want in a tire profile, there are quite a bit of variables to fine-tune. And tire manufacturers definitely do put a lot of effort into turning what comes out of a tree into the most refined black gold to put on your wheels.
Explained: Single compound, dual compound & triple compound
Now, I mentioned the balance a bike tire has to strike between riding characteristics. This is especially true for mountain bike tires because of the wide variety of surfaces, temperatures and riding styles there are.
One single compound cannot provide the best grip, rolling resistance, damping AND durability all at once. These demands are contradictory to each other, so a single compound can never provide the answer to everything.
Accordingly, there are a couple of tire compound numbers varying in complexity. For mountain bike tires you can choose between single compounds (1C), dual compounds (2C), and triple compounds (3C). There is in fact even a quadruple compound (4C), that is currently only made by Vittoria.
This basically means that tire manufacturers put firm rubber on the bottom for support, medium rubber along the middle (that provides traction but also doesn’t wear out so fast), and then some softer, slower rebounding rubber on the side (that’s where your cornering grip comes from).
The idea is to put the grippy compound where it meets the ground, the longer-lasting compound in the middle, and the hard compound at the bottom for support.
This compound layering technology allows for fine-tuning each section of the tire tread separately based on the desired characteristics. If you want to pull out the magnifying glasses and learn in great detail how each part of an MTB tire tread works, have I got the article for you.
Let’s crack on with the different compound layers you can mount on your mountain goat.
Single compound (1C) MTB tires
Let’s start off easy with the 1C bike tires, where the entire tire tread is made out of a single rubber compound. Single compounds are actually rare on mountain bike tires and more common on road, gravel and commuter bikes.
Being a single compound tire actually doesn’t tell you much information. How it handles and under what conditions it performs best is based on the firmness of the individual compound used. For example, a commuter tire would have to be the most durable and firmest. A mountain bike tire, that has to conform to uneven or wet terrain has to be the softest. A tire for hard-pack conditions would have to be somewhere in the middle.
Dual compound (2C) MTB tires
With dual compounds, there are actually two ways they are designed.
Dual layer 2C
The first is a dual layer compound. This means the tire tread is made up of two different layers of rubber on top of each other. There’s the stiffer base layer, that provides support for the knobs to push against, durability and puncture resistance. And the actual compound digging into the dirt is a softer variant, that conforms to the ground better but is also less durable.
As I discuss in my deep dive on how MTB tread patterns work, the center tread and shoulder knobs actually have different jobs to do. The middle of the tread has to withstand greater forces under braking, while the side lugs are responsible for cornering grip under lesser force. So having the surface tread layer be out of one and the same compound may not be the best in all scenarios.
Dual tread 2C
That’s where dual tread compounds come in, the other variation of a 2C compound.
Instead of the common base layer, the center and shoulder areas are entirely made out of different rubbers. The center knobs are stiff and durable while the side knobs are softer, more conforming for traction.
This allows the tire to have low rolling resistance, high braking traction and more durability. Still, the softer side provides the grip and control while cornering.
Triple compound (3C) MTB tires
Enter triple compound bike tires. They combine both of the dual compound versions with a firm, durable base layer and varying layers on the center tread and shoulder tread.
In a 3C tire, the softest slow-rebound rubber compounds are used to offer cornering traction, medium compounds on the center surface for a compromise between traction and durability, and a hard base layer beneath the entire tread for support and puncture protection.
Maxxis is the only major tire manufacturer producing 3C triple compound bicycle tires. Schwalbe had the Triple Star 3C compounds that got replaced by Addix (likely 2C).
Quadruple compound (4C) MTB Tires
Say what? Yes, there are actually quadruple compound bike tires out there. However, they are very uncommon. So rare even, that only one manufacturer, Italian brand Vittoria, is the only one making such a bike tire. And it’s no easy feat. They had to get a dedicated $ 1.5 million machine to even be able to do it.
Their 4C is basically a dual tread compound … doubled.
What I mean by that is the center tread and shoulder tread are different rubbers. But each area is not made out of one compound, but two. Here’s what this means in the illustration:
- Soft and grippy
- Firm and durable
- Firm and durable
- Soft but puncture resistant
The soft layer number 4 is what’s unusual compared to the other compound variations.
What’s the benefit of a 4C tire?
More rubber layers mean more control over how the tire performs in general. The stiffer side knobs with a softer top layer on top provide grip and support in the corners, while a softer base compound combined with a more durable top layer in the center of the tread improves braking traction without sacrificing durability.
