Mountain Bike Tires 101

Tread Pattern

Tread pattern tends to be the main thing that people look at when buying a tire, and tires tend to be named after their tread pattern. For example, a Schwalbe Nobby Nic is a particular tread pattern, even though the Nobby Nic is available in a bunch of different diameters, widths, rubber compounds, and casing configurations. So if someone says they’re selling you a Nobby Nic, you generally know what the tread pattern will look like, but you still don’t know a lot of the other details about the tire (and those other differences can have a pretty substantial impact on the tire’s price and performance). We’ll get into those other differences below, but first: the tread.

There are a lot of different considerations when looking at a tire’s tread pattern, and all of them are going to work together to dictate how the tire is going to ride. Ultimately, I find that the best way to figure out what tires you’ll like is to ride a few options and look at the differences between the ones you like and the ones you don’t like. But that takes time and money, so here’s a quick-ish rundown of some things to look at.

Transitional Knobs

Whether a tire has transitional knobs is, in my mind, the single most noticeable factor in the tread pattern that determines how a tire rides.

Most mountain bike tires are going to have knobs down the middle – those help with all things that happen while the bike is going in a straight line. Climbing traction and braking traction mostly come from those knobs.

Most mountain bike tires also have knobs along the sides. Those are your cornering knobs, and take care of business when the bike is leaned over in a turn.

Transitional knobs are any knobs that fall in between these two sets. Some tires have them, and some don’t, and that’s because there are two competing theories at play here.

Here’s a picture of a Kenda Nevegal (left) and a Maxxis DHR II (right). The Nevegal has transitional knobs, while the DHRII doesn’t.

The argument in favor of transitional knobs is that they help maintain traction in mild corners where the bike isn’t leaned way over, and they provide a more seamless cornering experience when rolling into a tighter corner. Some degree of traction is maintained at all lean angles (at least until you run out of traction when leaned way over, past the side knobs).

The argument against transitional knobs is that they limit the ultimate amount of cornering traction available. In a hard corner, you get the most traction when your side knobs are fully dug into the ground. The more pressure you can put on those knobs, the harder they’ll dig in, the more traction they’ll produce, and the faster you can go around that corner. The issue with transitional knobs is that they’re placed just inboard of those side knobs, so they effectively take pressure off the side knobs. Less pressure means those side knobs can’t dig in as hard, which means you can’t corner as hard.

But the lack of transitional knobs means there’s a gap in the tread pattern. There are center knobs in the middle and side knobs on the edge, but nothing in between. This will generally manifest itself as a drifty or loose feeling as the bike is leaned into a turn. The bike has traction when it’s upright, and it has traction when it’s fully leaned over, but it’ll tend to slide a bit in between.

That drifty, loose feeling takes some getting used to, and with many tires, it can take a bit more commitment in a corner. Understandably, not everyone likes that. Which is why there are a lot of good tires on the market with transitional knobs, and a lot of good tires without.

The distinction between tires with transitional knobs and tires without isn’t always crystal clear. Take a look at the picture below with (from left to right) a Bontrager G5, a WTB Trail Boss, a Maxxis Ardent, a Schwalbe Hans Dampf, and a Maxxis Griffin. The G5 on the left clearly does not have transitional knobs. The Griffin and the Hans Dampf on the right pretty clearly do have transitional knobs. The Ardent has some transitional knobs, but they’re fairly minimal. The Trail Boss doesn’t have clearly defined transitional knobs, but the rows of center knobs get pretty close to the side knobs, so they probably act like transitional knobs to some degree. Long story short: not all tread patterns fall clearly into one category or another.

There’s no right or wrong answer in the transitional knob debate, and much of it will come down to personal preference and where you ride. If you don’t know where to start, I’d go with a tire with transitional knobs if your trails are primarily hardpacked or if you’re not comfortable with the bike sliding around a little bit. I’d go with a tire without transitional knobs if you’re riding more soft dirt and you’re looking for maximum cornering traction.

Beyond the transitional knob discussion, there’s a bunch of other little features that are worth considering:

Knob Height

This is pretty straightforward – taller knobs will dig in better in soft dirt and sand, but they’ll roll slower and they can feel squirmy on hard packed trails. Usually, tires with really low knobs are geared towards cross country trails. The tallest knobs are usually found on mud tires, but those are pretty condition-specific, so I wouldn’t recommend them unless you’re riding in a lot of mud.

I tend to pay attention to the height of the center knobs relative to the side knobs. If the side knobs are big and tall (relative to the center knobs), it means that I won’t have to lean the bike over as far to get those side knobs to begin to engage. If the side knobs are relatively short, then I have to lean farther to get them to hook up, and it also means there’s less meat there to hook into soft dirt. One downside of taller side knobs is they can feel squirmy and slow, especially on hard-packed dirt.

Knob Spacing

Aside from the whole transitional knobs discussion, some tires have tightly spaced knobs, and some have a more open spacing.

Tightly spaced knobs tend to roll faster, and they tend to feel less squirmy on hardpack. Wider spaced knobs tend to dig into soft dirt better, and they also tend to shed mud a bit better, but they can feel like tractor tires on hardpack.

Below is a picture of a WTB Beeline (left) and a Maxxis Wetscream (right). The Beeline is pretty clearly a tire for dry conditions and harder packed trails, whereas the Wetscream is a mud tire that won’t work particularly well in anything but the wettest, softest, muckiest conditions.

Center Knob Shape

Longer horizontal knobs will generally help with climbing and braking traction (think of them as big paddles) but they also tend to roll a bit slower. Many center knobs will be ramped on the leading edge, which sacrifices a bit of climbing traction in the name of helping rolling resistance. I’ve also occasionally seen knobs which are ramped on the trailing edge, which sacrifices braking traction in the name of trying to make a tire that looks different and cool. Tires with that feature should be burned in an environmentally conscious manner.

Side Knob Shape

Side knobs tend to be a bit more homogeneous among different brands, but basically, chunky blocks provide good cornering traction. Many tires will have some offset knobs, “L” shaped knobs, or other “hooks” in the knob. All of those shapes help with braking traction while the bike is leaned over.

Knob Orientation

Somewhat like transitional knobs, I tend to split tires into two categories: tires where all of the knobs are cut and shaped more or less in line with the direction of travel, and tires where there are a bunch of knobs at weird angles.

An example where the knobs are more or less in the direction of travel is something like the Schwalbe Magic Mary – the side knobs are tweaked a bit to provide some braking traction in corners, but the center knobs are all squared off and straight. A Schwalbe Hans Dampf is an example that has a bunch of knobs at weird angles.

Knobs at weird angles can help make the traction a bit more diverse (that’s an odd way to describe traction, but I’m going with it). They hook up in a wider variety of directions. But they can also make traction a bit less predictable, and they don’t always grip in the direction that you want when you want it. The practical implication is that sometimes they work pretty well, sometimes they’re terrible, it can be pretty tough to predict what’s going to be what just by looking at them.

Siping

Lots of tires will use sipes, which are little cuts in the knobs. This helps the knobs flex and grip under load, and can do wonders for improving traction on wet roots and other greasy surfaces. Sipes across the direction of travel will tend to help with climbing and braking traction. Sipes parallel to the direction of travel will tend to help with cornering traction. Diagonal sipes do a bit of both.

Buttressing

Lots of tires have raised bits of rubber that aren’t really knobs, per se, but they supposedly provide a bit of support for the knobs by buttressing the sides. In large part, I’m of the opinion that buttresses are there mostly to look cool and help sell tires, but they probably do provide a marginal benefit in some situations.

A Side Note on Tread Patterns and Sizing

It’s worth noting that not all tires with a given tread pattern are exactly the same throughout the lineup. Using the Maxxis DHF as an example – while the tread more or less looks the same, there are some subtle differences between a narrower DHF and a wider DHF. At the risk of stating the obvious, the lugs on a 29 x 2.3” DHF aren’t exactly the same as the lugs on the 27.5 x 2.8” DHF. Lots of tires from pretty much all of the companies have those same variations, so my point is just that, if you’re reading reviews of a given tread pattern, pay attention to the size that was reviewed. It may ride a bit differently than a narrower (or wider) version.

Another Side Note of Front vs. Rear.

Plenty of people happily run the same tread pattern front and rear, but there are a lot of tires that are intended for use as a front or rear. Using the Maxxis DHF and DHRII as examples – those letters stand for Downhill Front, and Downhill Rear. Plenty of people have run front tires in the rear and vice-versa (and some companies have actually spec’d their bikes with a DHRII in the front), but if you’re unsure of what’ll work best, stick with the manufacturer’s recommendations to start. And some tires, like a Specialized Slaughter, just work a lot better as a rear tire. The general rule is, if you’re running different tires front and rear, you’ll generally want to run the knobbier, more aggressive tire in the front.

NEXT: Casing and Construction