Mountain Tires: The Devil in the Details
Let’s start with the basics – tread patterns. Understanding tread patterns is the the first step in understanding the relationship between your tires and the dirt below. Whether you’re looking for more traction and control, or a lighter, faster- rolling tire, understanding the tread will lead you in the right direction from the start. Tire treads fall along a predictable spectrum with smaller, shallower, and more tightly-spaced knobs on the faster/lighter end of the spectrum, and bigger, deeper, and more widely-spaced knobs on the grippier, heavier end of the spectrum. Smaller, shallower, more tightly-spaced treads will be lighter and quicker rolling, but less grippy and confidence inspiring, while bigger, deeper, more widely-spaced treads will offer better grip and control, but will also be heavier and slower rolling (shown below).
Typically, faster/lighter tires will be found on shorter travel bikes and grippier/heavier tires will be found on longer travel bikes. This is because tire performance is always a trade-off between the two ends of the spectrum and bike companies are trying to spec the most advantageous set of tire attributes for each category of bike they sell. But that doesn't mean that the type of bike you ride has to define exactly what tire you choose. Just like different bikes provide different riding charcteristics and experiences, tires can be used to create a unique experience for you regardless of the bike you're on. For example, here at the shop we often recommend putting grippier, heavier-duty tread, like the DHF or the Aggressor on even short travel trail and XC bikes because they can dramatically increase your cornering confidence and fun-factor. On the flip side, if you have a burlier trail or enduro bike that you'd like to lighten up, and you're ok with giving up some traction and control, swapping to a lighter/faster tread could also be an attractive option. Understanding the way that different treads offer different trade-offs in performance will make it easier to choose exactly the right tire for your bike and for the way that you want to ride!
With tire casings, just think durability. However, with more durability comes more weight. With Maxxis, you’ll see EXO, EXO+, Double Down(DD), and sometimes Downhill (DH) casing options. But there are other protection and casing technologies that exist within the Maxxis Tire lineup (see more puncture technologies here). Most bikes we sell will come with EXO or EXO+ casings as shipped from the manufacturer. These two casings give you a respectable amount of durability and protection while keeping the total bike weight lower. The EXO is commonly found on stock builds, and gives the tire a reinforced side-wall - while EXO+ has the same side-wall reinforcement, but extends it all the way from bead-to-bead. Thus, gaining a protective layer under the tread that doesn't come with the standard EXO casing. In practice though, we've found that for riders who really need or want more durability than an EXO casing, the Double Down casing tends to be a better option. That's why we choose to stock primarily EXO and DD tire options instead of the EXO+.
Double Down (DD) casings consist of two 120tpi casing layers reinforced with a butyl insert that extends the bead of the tire up into the sidewall. This gives you a significant increase in durability and resistance to cuts and abrasions. This reinforcement is visible on the surface when compared to an EXO/EXO+ (as shown below). In addition to that added protection, DD casings are stiffer and will provide additional sidewall support at lower tire pressures, reducing the likelihood of lateral squirm under heavy cornering. We typically recommend Double Down casings for riders who have either had past issues with punctures and tears, or who ride aggresively through technical terrain and expereience a high degree of lateral load (AKA Drifty McSkiderson) on their tires. Many riders who are concerned about the added weight penalty will opt to only run the DD casing in the rear since the rear is more susceptible to damage and abrasion than the front.
Tire compounds vary in terms of the the softness or hardness of the rubber (sometimes refered to as durometer), and in the arrangements of those rubbers to give you a faster-rolling or more grippy tire. Maxxis uses a triple compound(3C) and dual compound (2C) for most MTB tires. 3C tires will be more expensive and use three different rubber compounds along the tread surface while 2C tires will be less expensive and use only two different compounds. Typically the center-line of the tread surface will be made from a firmer rubber for longer wear-life and lower rolling resistance while the edges of the tread will use a softer rubber to increase grip and control.
*2C isn’t branded on the tire like all the other information, and is assumed when “3C…” is absent.
Within their 3C tire offerings, Maxxis uses three different blends of rubber compound to achieve different perfofmance goals:
3C MAXXSPEED: Harder and faster-rolling, but less sticky--Typical of XC Race tires
3C MAXXTERRA: Softer and stickier, but less fast-rolling--Typical of Trail/Enduro tires
3C MAXXGRIP: Softest and stickiest, but with greater rolling resistance and reduced wear-life--Typical of Enduro/DH tires
We also often see riders opting for different rubber combounds front and rear. Since the rear tire is prone to faster tread wear, avoiding the softest compounds can mean increased life out of your tire and less frequent replacement. For example, a 3C MAXXGRIP front tire will deliver excellent traction up front where you need it and a 3C MAXXTERRA rear tire will still grip very well but without requiring replacement as often as a 3C MAXXGRIP would. 2C tires tend to offer an excellent balance of stickiness and wear-life and are generally more simliar to 3C tires with a MAXTERRA compound than they are to either MAXXSPEED or MAXXGRIP compounds, though this will vary somewhat depending on the intended usage and tread pattern of the tire you're looking at.
Keep in mind that the rubber compound and the tread pattern work together to determine the type of grip and traction you get on the trail. Between the two, the type of tread will have a bigger influence on over-all grip than the choice of rubber compound will. That means that a MAXXGRIP tire with a shallower tread, will still be less grippy than a MAXXTERRA tire with a beefier tread.
The TPI of a tire refers to the density of the threads used in the underlying casing. It describes how many Threads Per Inch there are used to construct the casing itself. The most common options are 60tpi and 120tpi. Each of these has its trade-offs, so seeing one as being "better" than the other depends a lot on what you want out of the tire. 60tpi tires have fewer, thicker threads that give the tire more durability and better puncture, cut, and abrasion resistance but they'll generally be stiffer and less supple than higher TPI options. 120tpi tires have a greater number of finer threads that allow the tire to better conform to the terrain and create a smoother more supple ride and more predictable handling. Because high-end, light weight road tires are often higher TPI, some people assume that higher TPI also means lighter weight, but that's not necessarily the case. For example, Double Down casings are both higher TPI and heavier than their 60TPI cousins.
There you have it – tires simplified! Mostly... Tires can either be a headache to choose on or an exciting opportunity for you to get the most out of your bike. If you want to change your ride experience or give your bike a different flavor on the trail, hopefully the information in this article, will help to steer you in the right direction. If you're interested in learning more, stop by the shop and chat with one of our super-star sales staff!