There are more options in tire design and construction than perhaps any other part of your bike; choosing wisely can make a huge difference. Ryan Dunfee photo.
Tires are confusing. Riders must consider tire width, knobs, rim width, intended use, price, rubber durometer, one, two or three extrusion layups, casing plies, casing tpi, sidewall protection, and a whole host of buzzwords unique to each manufacturer. All before you even think about how much air to put in it.
However, few buying choices have more impact on, or can better improve, your ride than tires—they are literally where rubber meets trail—so cowboy up and let’s get after it!
RELATED: Improve your dry-conditions riding technique
Ken Avery at Vittoria and Bobby Brown at Maxxis, two companies leading mountain bike tire technology, were kind enough to lend their expertise for this piece.
Jesse Melamed on the new Maxxis recon + tires. John Gibson photo.
Maxxis is, of course, a monster of an MTB company with a long history of great tires, from the Minion to the High Roller to the IKON.
Vittoria is a smaller company with a strong road pedigree, where rubber compounds are intensely scrutinized. Their investments in tech are now rolling into mountain bikes tires.
Tire parts roadmap. Study it well. Vittoria illustration.
Traditionally, tires are a tradeoff between grip, rolling resistance, wear, and weight. To mitigate some of that tradeoff; Vittoria has dropped strong R&D into new compound and layup technologies, Maxxis has developed new profile designs and casings.
Some of the steps for discovering the right tires (below) differed slightly between Ken at Vittoria and Bobby at Maxxis, but overall were consistent. So feel free to think about this list holistically, digging into different parts as you do your tires research.
So, how does your average rider choose the right tire?
#1: Know (or figure out) your discipline or rider profile
Anneke Beerten, hauling ass in an Enduro World Series race, where she'll use pretty burly and knobby tires to deal with the demanding and technical courses. Vittoria photo
Ken/Vittoria: It’s critical to start by asking what type of rider you are. Do you ride XC, where light weight and rolling speed are priority? Or are you more focused on downhill, where grip and strength are what you need most? Or are you somewhere in between?
Think about where on the XC to DH spectrum you most comfortably fit. If you're looking to buy multiple sets of tires, think about which types of rides you're trying to excel at with your purchase.
#2: Match up a width and knob design for that rider profile
The The Mezcal XC tire. Note the fast-rolling center design - and lots of transition knobs between center and side. Vittoria photo
Bobby/Maxxis: Let’s say you’re into cross-country riding. You’ll need something like the IKON with short, fast knobs. Or, for all-mountain riding with more focus on shredding the downs, something like the Ardent or High Roller II, that deliver more beef and bite.
Ken/Vittoria: For Vittoria, the Mezcal is our XC tire, which has much lower-profile knobs in the center so it can roll faster. The Morsa is for all-mountain and enduro riding, and it has much bigger knobs overall and more pronounced cornering knobs especially.
TGR: Generally, XC and fast-rolling tires have shorter knobs, are thinner, and are mounted on narrower rims. Vittoria and Maxxis have their tires grouped by discipline on their websites. So get in the ballpark quickly by browsing there.
#3: Consider different tread patterns based on the terrain you most often ride
The Vittoria Morsa all-mountain tire. Burly, good in the wet, and still pretty fast. Not a lot of transition knobs, and beefy side knobs for solid cornering. Vittoria photo.
TGR: Tread design is really magic; how the knobs are spaced, whether there are 'transition' knobs between center and edge knobs, and how they are shaped and ramped all impact how a tire rides and performs. Some companies offer multiple tire types and patterns for any single rider profile.
Ken/Vittoria: Hardpack surfaces do not require a deep tread. Mud absolutely requires a deep tread. But–pro tip!–you should also pay attention to how far apart the knobs are spaced. The trick is to have enough negative space between knobs for the sides of them to grab that root or rock. And that spacing can vary based on the terrain you're trying to match.
Maxxis' Wetscream: built for mud. Just mud. You do not want to be rolling this around around on hardpack trails mid-summer unless you want an extra workout from the added rolling resistance. Maxxis photo
Also, once your tire grabs onto trail features, you want the knob to react a certain way on roots and dirt, or hardpack and cornering speed. This can be about ‘sipes’ as well as rubber type.
You know how you hear basketball player’s shoes squeak during a game? That’s from the ‘sipes’, or grooves, in the tread. Sipes in basketball shoes allows the rubber to flex and grab onto the slick court surface. Tires are built with the same idea. The tops of all knobs have sipes cut in them to counter certain forces.
#4: Sidewall protection: how much do you really need?
Vittoria's Mezcal, which is a lighter sidewall XC tire. Gunnar Waldman photo.
Bobby/Maxxis: Do you ride a lot of rocks? Or not so much? The more protection you get, the more weight you carry. That’s kind of the choice.
For Maxxis, EXO is our lightest sidewall protection. It adds 50 grams per tire [most mountain bike tires weigh between 700-1200 grams each], which is a small weight increase in weight for a huge upgrade in reliability. It's basically the same increase in weight as using a little extra tubeless sealant.
The Maxxis IKON. An XC tire with added EXO sidewall protection and short knobs. You can see there's lots of knobs to transition from center to side. Maxxis photo.
Then, in the middle of the bell curve, Double Down (DD) is Maxxis' next level of protection, which adds 150 grams on top of EXO with a lightweight dual-ply construction.
Maxxis' new Aggressor tire with Double Down Sidewall. Note the lack of transition knobs - advanced tire. Maxxis photo.
The dual-play DD design is a little burlier with a stiffer sidewall design, which is necessary for today's wider rims. And the casing is a lot tougher. Yet it maintains a reasonable weight due to a lighter weight 120 TPI casing fabric.
The idea is to get light and tough. For enduro races, you’re out there a long time and need to be efficient. But courses are hard, so they need to still run like a DH tire.
And, for downhill-only riding, it’s the DH casing, which adds 200 grams on top of a DD sidewall with two-ply construction and a wire bead. It’s literally twice the weight of our lightest tire. But the protection is there.
When Maxxis is designing any tire, we think about how much ‘spring’ or ‘damping’ a tire should have, as well as how much cushion there is between the tire and the rim, should you bottom out. That will be modulated with a butyl insert on the sidewall, tuned to provide a rim cushion for bottom-out protection, or additional sidewall support for high-speed cornering.
Gunnar doing a little 'deflection' testing. Dave Peters photo.
Using air pressure, the rider will want to find that place where the tire sags in and absorbs the initial impact of the terrain, but doesn’t bottom out and hit the rim. Heavier sidewalls act like more compression damping suspension.
Ken/Vittoria: Tire sidewalls affect a tire’s weight, rebound and damping characteristics, like casing. Slightly counter-intuitively, it’s been noticed that a harder tire sidewall does not necessarily increase speed.
Needin' me some sidewall protection. Vittoria photo.
A softer sidewall will give more, true, but a harder one will cause you to deflect off obstacles, which can also rob speed. Studies have shown how reducing deflection speeds you up. A softer tire also grabs terrain more efficiently, adding traction.
#5: Choosing your tire's rubber compound
Too soft, too hard, or goldilocks? A softer tire will usually grip better, but wear faster. Ryan Dunfee photo.
TGR: Tire company's compounds are proprietary, but the goal is to try to find that right balance of rubber hardness (durometer) and viscoelastic properties (rebound or response when under pressure). Rule of thumb is the softer the rubber the better it grips and the faster it wears. And also, the more varied the rubber compounds on any given tire, the more expensive the tire.
Ken/Vittoria: You need the ‘effective edges’ (those that are contacting the features of the terrain) of the knobs to grab, but still dig and not turn to mush. Vittoria has innovated in this space. We add a 'pristine' variety of Directa Plus Graphene, called G+, which is a thin sheet of pure carbon just 2-8 atoms thick to our performance rubber compounds. It allows the rubber to rebound differently by changing its elastomeric properties. It's loosely analogous to 3DO or impact gels, as the compound’s molecules align differently under different stresses. The rubber firms up when rolling straight and then, under cornering or traction loads, softens to rebound slower.
We also have a slightly different approach to layup. We use a very complex 4C extruder process proprietary to Vittoria.
4C allows Vittoria to put different layers of rubber compounds in all areas, not just separate tracks on the tire. In any given area, we will use stiffer rubber at the base of a knob and a softer layer at the top of the knob. This is so the knob doesn’t pivot on its base, but flexes progressively as more force is transferred to the tire. This allows your tread pattern to stay consistent, or 'undeformed,' under forces, maintaining grip through varied conditions.
Choose wisely. Knowing what kind of traction to look for for your specific ride style is key. Vittoria photo.
Bobby/Maxxis: There is a 'shore durometer' (hardness) number to all rubber that some manufacturers release, but going solely by that is often misleading. Stickiness/friction and different compounds added to rubber during manufacturing can change the longevity and grip of the rubber at any given hardness level. It’s important to know that, in general, a softer rubber is slower rebounding and faster wearing. By 'rebounding,' we mean the pushback from trail features and forces–kind of like a fork or shock’s rebound dampening suspension adjustment.
Briefly, Maxxis tires can have one or multiple compounds in them, which are:
Single compound: the hardest compound (though on DH tires, single compound comes soft) and is cheapest because it’s easiest to manufacture.
Dual compound: most versatile, softer on sides, harder in the middle.
Triple compound (3C Maxx Terra): Center knobs are hard, cornering knobs are soft, and we use a hard base layer to optimize rolling resistance. Generally, this is the most expensive option.
Also, in general, XC tires use harder rubber, enduro tires use medium or mixed compounds, and DH tires are soft and sticky, but built burly.
Finally, the wetter conditions you ride, the softer the rubber you want. In the desert, you can have the harder rubber for longer wear.
#6: Figure Out How Thick Your Casing Needs To Be
Vittoria's Morsa tire with TNT casing and sidewall protection badging. Vittoria photo.
Ken/Vittoria: Casing is the protective layer that runs bead-to-bead and gives a tire its flex characteristics. Vittoria's premium casing is TNT, and stands for TubeNoTube (tubeless ready casing). There’s also 'foldable' and 'rigid,' and rigid has a wire bead and is a good price option, but heavier. To be clear, TNT is a ‘foldable’ tire, and has the better bead. Also, TNT tires will have the better rubber compounds.
Pick your sidewall and casing to match, soft or hard. Casing TPI counts typically run 60 to 150 (in mountain bike tires), and higher counts use thinner threads and will therefore flex more and be softer.
Rachel Throop. Casing, but never cases. Jake Hamm photo.
Often, tires are designed with just the right casing for their intended use anyways, making the choice simple. On TNT casing XC tires, there’s a sidewall protection layer that protects against tears. On the all-mountain/enduro TNT tires, we take that XC casing and add an APF insert just above the bead, which is tuned to cushion impacts. On the DH casing (rTNT), we use a 2-ply casing over the whole tire, an APF insert, and a special rigid bead.
Each casing type is tuned for its specific use, ensuring the best performance.
Bobby/Maxxis: Higher TPI, like 170, is softer, and lower, like 60, is harder. And you can have single or double ply. Again, all this affects weight. And tires are a part of that precious rotational weight equation, as a pound removed from your wheels is going to make a much bigger difference in the speed of your bike than a pound off your frame.
#7: Buy the right size tires for your rim
Wide for wide, narrow for narrow. Maxxis photo
TGR: Tires are absolutely designed around rim widths. So even once you've figured out the riding style, knob profile, sidewall, rubber and casing, keep in mind that you shouldn't go out and run a very wide tire on a narrow rim, or vice versa. Generally, if you're running a rim wider than 30 mm, you'll want a wider tire (2.3-2.5"). If you're running a narrow rim–something closer to 20 mm–you'll want a narrower tire (1.9-2.2"), even though getting a wide one might be tempting.
The trend now is to run ever-wider rims. Below is a brief video from the folks at IBIS on new wider rim width designs.
Bobby/Maxxis: Maxxis' Wide Trail (WT hotpatch on the tire's side) tires are optimized for today’s wider rims. Wide Trail tires are 2.4-2.5" and designed around a 30-35mm inner rim width. They are essentially designed to correct the knob profile and tire shape when used on wider rims.
Wide Trail knobs are spaced differently to take advantage of the way a tire sits on a specific rim. If you put a narrow tire on a wide rim, that will square off its profile, meaning instead of the side knobs leaning off at 45º, which optimizes cornering, you’ll get a drastic falloff (making the side knobs more vertical, increasing contact patch in a straight line and decreasing the contact patch when leaned over). That's a bad tradeoff for greater volume.
So, with a wider rim and small tire, you’ll get better volume, but worse cornering or ‘lean angle’ cornering. WT tires are designed with an ideal profile to match performance on wider trail bike rims.
TGR: Don't worry, as all tires are offered in a variety of widths. But buying the right size for your rim will ensure the knob profile will perform as designed and not be too 'round' (wide tire on a narrow rim) or 'flat' (narrow tire on a fat rim). Also, although it's tempting, don't under-inflate tires for more grip. Please. You can run them soft, but don't get nuts. Wide tires on narrow rims at low pressures squirm.
The Bottom Line On Choosing Your Next Tire
By this point, you have gobs of information–hopefully enough to have an even better time on your bike next time out. Ryan Dunfee photo.
TGR: There's enough information here and on manufacturer's sites to get you VERY close. Trust your homework. If you do it, you'll be riding a more helpful tire than you have now.
Bobby/Maxxis: Plus tires are here to stay. They work really well for a lot of people, so it’s where things are headed. You can set up a many different ways with different tires. Really trying to balance both weight and durability. So we’re offering some solid innovation and choices in that size.
TGR: Some folks like to run wider tires in front than in back. And it makes a lot of sense, as power from the rear is usually applied when the tire is straight up, so massive volumes and side knobs are not as important. Wider tires and burlier knobs on the front tire, which initiates cornering forces, can help you dig in and plow through your corners. We should note, though, that this decision can also be a bit of a wormhole.
Do you ride more centered, more front or off the back? Do you like tires that break evenly and predictably? Maybe having the same tire front and back is your jam. Or if you like the security of knowing your front tire is NEVER going to wash out - then maybe bigger front rubber is for you.
You will still follow the steps above and don't vary massively front and back; modulate sensibly. I've run a Maxxis Minion 2.5" front and Ardent 2.4" back and been happy. I've also run matching Vittoria Morsa 2.3" tires front and back and been in love with that.
And for God's sake, buy a good tire gauge and inflate your new tires properly, because if you don't do that, all this is for naught.
TGR will be releasing some reviews on Vittoria tires in the near future, and rides on the Morsa and Mezcal have been incredibly promising.
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About The Author
stash member Gunnar Waldman
Editor-at-Large, IMBA instructor and east-coaster. Raced Trans-Savoie in France, SoCal Enduro and Endurance in Temecula and is psyched for all the great new races in the east. Article Ideas: gunnar.waldman@tetongravity.com
JohnBoy
May 26th, 2016
Finally tires demystified. Good job Gunnar