I can’t think of any other category within the bicycle world that offers such nuanced purchase options than that of mountain bike tires. Casing, compound, sidewall treatments, bead options, knob size and spacing, and overall size represent the many variables that affect how a tire functions. There is no need to be intimidated by the technology however. By following just a few basic rules you can narrow down your choices to a manageable number with little effort.
At Art’s we do everything we can to take the guesswork out of tire purchasing. One big challenge regarding tire purchasing is the massive variance between the marked width of a tire and the actual width, as well as the difference between a manufacturer’s claimed weight and actual weight. In order to account for this we measure and weigh a sample of every performance tire we carry. We publish all of the actual widths and weights in the “Features” tab on every tire description page so you know what you are getting. This same tab also contains information such as the weight of the specific variants of a given tread model along with casing information. We also have a tire performance guide at the bottom of the description showing the range of applications for a given tread pattern. Lastly, we often outline in the description the type of terrain that the tire excels in.
Yet, armed with this information it is still helpful to have a guide to understand what options are available and where to start looking when choosing a tire. Below I have assembled a guide for our customers that explains and defines the various options available across the board with respect to tires. My hope is that this offers a basic primer to understanding why mountain bike tires are offered with so many options and how to decide which one is right for you.
Tread knobs that rise to a point or spike such as those found on the Maxxis Medusa or WTB Wolverine are primarily made for wet weather and mud. Low, tightly spaced knobs like those found on the Schwalbe Racing Ralph, WTB Weirwolf LT, Maxxis Ikon, Maxxis Aspen, Maxxis Crossmark, and Kenda Slant 6 are for hardpacked clay and/or loose sand. Medium height knobs with medium spacing like those on a Schwalbe Nobby Nic, WTB Bronson, or Maxxis Ardent represent an all-conditions tire. Large knobs found on tires such as the Continental Trail King, Maxxis High Roller, and Schwalbe Hans Dampf that are spaced far apart are best in rocky conditions or in loamy soil.
Casings and Sidewall Treatments
Tire casings (sometimes called “carcass”) is the fabric that is underneath the exterior rubber that acts as the skeleton of the tire. Casings with high thread counts per inch (typically denoted as TPI) have an especially supple feel and smooth ride quality. A common high TPI mountain tire will have 127TPI. While an especially supple casing is something that everyone wants, high TPI tire casings become fragile as a result. This limits high TPI tires for use primarily on smooth hardpacked trails. 60TPI is the most common and represents a medium TPI. Tires made with 60TPI casings are more durable, yet are heavier and lack the suppleness of 127TPI tires.
UST casings are made to a universal tubeless standard that requires an additional layer of rubber that extends from bead to bead so that the tire can be theoretically used without sealant. This additional rubber adds weight and stiffens the tire, but it can also serve as an effective layer of armor to protect the sidewall from cuts should you live in an area with sharp rocks or flora.
Lightweight armored casings vary widely from brand to brand and are typically offered in conjunction with a tubeless bead and described as “tubeless compatible,” rather than marked UST. Such tires typically have 60TPI and require the use of sealant to plug the micro pores in the casing that are absent in UST tires. “Tubeless compatible” casings are the most popular type, as they offer a good compromise between the various casing options. Examples of this casing include Continental’s RTR, Schwalbe’s EVO Snakeskin, WTB’s AM TCS found on their Bronson and Weirwolf tires, Maxxis’ Exo, and Specialized’s Control casing.
Finally, there are tubeless compatible versions of high TPI casings that offer light weight and a supple ride. They have the same limitations as those mentioned earlier for high TPI casings and require sealant for the same reason all tubeless compatible tires do. The extra thinness and subsequent porosity of this type of casing makes it even more reliant on sealant than their lightweight armored brethren but it is well worth it if you want the lightest, fastest rolling tires available. Examples include Specialized’s S-Works tires, Schwalbe’s EVO non-Snakeskin casing, and Continental’s Supersonic casing.
Bead choices can be divided into Kevlar, wire, carbon, tubeless, and UST. To make it easy however, they can be simply divided into either tubeless or non-tubeless. If you plan to run your tires tubeless, make sure you get a tire with a tubeless bead. Tubeless beaded tires seal better, air up and seat more easily, and are far less likely to burp air or blow off the rim under hard cornering. If the tire is described as “tubeless compatible” or conforms to the UST standard then it has a tubeless bead. If it is labeled as anything else it is not tubeless compatible.
Different rubber compounds can dramatically change the way a mountain bike tire handles. These compounds are normally expressed using a shore hardness number that corresponds to the tire’s durometer. Soft compound tires generally have a durometer between 42 and 55. 60 is considered an all-around to slightly-hard compound. 62 to 70 are considered hard compounds.
Soft compounds tend to favor descending performance over climbing. The same qualities that make a soft compound grip the trail so well also cause poor rolling resistance. The opposite is true of harder compounds. Hard compounds have the additional benefit of a longer tread life
Tires made with a single compound use one durometer of rubber for the entire tread. Single compound tires can be great if you are at one end or another of the riding spectrum (i.e. downhill, or xc racing). However, multi-compounds try to make the best of both worlds and are the best option for trail riders. Most compounds in this category are dual compounds. Dual compound tires such as the Kenda Nevegal DTC utilize a strip of tread down the center made with a harder compound to improve rolling resistance and tread life. For the side knobs, these same tires will use a soft compound to provide improved cornering grip.
Triple compound tires such as Maxxis 3C, and Schwalbe PaceStar or TrailStar, use a hard base rubber that is capped with a softer compound in order to get a fast rolling tire that lasts long and grips well whether cornering or traveling in a straight line. Of course these triple compounds can vary based on application so make sure you get the right one for you. For Schwalbe you should choose the PaceStar compound if you value low rolling resistance over grip, and the TrailStar compound if the opposite holds true. Many brands do not offer compound options within a given tire model because they believe that they have optimized the compound to best complement the intended use and tread pattern. Examples of companies that take this approach are Continental and WTB. One last point on compound: soft compounds tend to perform better in wet conditions so take that into account when making your choice.
Narrow tires do best in either wet conditions or on smooth and flat trails. Knob shape and size will determine which condition a narrow tire is designed for (see section on knobbies). Wide tires are best for dry and/or rocky conditions as well as riders who primarily focus on downhill performance.
There are exceptions to this however. There is a massive selection these days of large casing tires that are made with small, tightly spaced knobs for smooth hardpacked conditions. The original example of this is the 2.4 WTB Mutano. Newer examples include the 2.3 Kenda Slant Six, and 2.2 Maxxis Ikon.
There is also a new class of tires being developed in the downhill world that is specifically aimed at performance in loamy dry conditions. These tires are a medium width and tend to have tapered, cut down spike knobbed tires. The best example of this is probably the Specialized Hillbilly. However, these tires also do well in intermediate wet conditions so some are marketed primarily as wet weather tires such as the Schwalbe Muddy Mary or Continental Baron.
Putting it All Together
As an example of how to take all of these tire variables and apply them to your purchase, I will start with myself: For my money I will not use any mountain bike tire that is not rated as tubeless compatible. I want the peace of mind, reliability, and improved traction that only true tubeless tires can offer. This eliminates a large portion of tires without tubeless beads or casings. I also know that I require tires made for dry conditions based on the climate I live in, so I can eliminate all wet weather options. Because sharp rocks thickly populate every trail in my area, I know that I need an armored sidewall and/or casing and large knobs to grab on to those rocks. As an aggressive trail rider, I know that only wider tires such as a 2.3-2.4 will suit me. Lastly, because I like to climb as much as I descend, I need a tire that has a double or triple compound to maximize rolling efficiency without sacrificing cornering ability. This narrows my choices to the Schwalbe Hans Dampf, Continental Trail King, Kenda Nevegal, Maxxis High Roller, and Maxxis Minion.
A good rule of thumb is to use a slightly narrower tire in the rear in order to reduce rotating weight that has to be driven at the pedals. Narrow rear tires also have the benefit of having the tendency to break loose before a wider front tire thereby adding safety and greater predictability when pushed to the limit. Because rear tires are weighted far more when climbing, a reduction in rolling resistance can also be of benefit if your trail conditions are not too loose. With my example, I might use a tire with a tread like the Schwalbe Nobby Nic or Maxxis Ardent during the seasons when the trails are not especially dusty. The majority of the year however I could use the same tread as I am using in the front, just in a narrower 2.2” wide option.
Some Final Thoughts
Because trail conditions change with the seasons I recommend having a set of wet weather and dry weather tires on hand so that you always have the right tool for the job when the time comes. That goes doubly sure if you do any racing. Why spend all that money on travel and race entry fees only to have tires hold you back? If you are really serious about racing, keep a set or two (one wet, one dry) of race day tires so you have fresh, fast rolling rubber when speed is all that matters.
Now that you know how to find the perfect tire; buy some, get out on the trail and revel in your newfound grip and speed!
Daniel Slusser is a professional bicycle mechanic with over ten years of experience. He holds a bachelor’s degree in business administration from HSU and a master’s degree in history from Cal Poly University. When he is not riding, wrenching, or writing he enjoys spending time with his wife and two children.