Mountain Bike Tires 101

Rubber Compounds

The rubber in most tires can more or less look the same, but it’s not. Most tire companies are offering many of their tires in more than one rubber compound, and each variation can ride pretty differently. Some rubber compounds are hard, which tends to make for a faster rolling tire that takes a long time to wear out. Some rubber compounds are softer, which tends to grip really well in corners and on slippery rocks and roots.

A lot of companies will use a softer rubber compound for their side knobs to improve cornering traction, but use a harder compound on their center knobs to help out with tire durability and rolling resistance. Some companies will also use multiple compounds with a single knob, building the base of the knob out of a harder compound, and then capping it with a softer, grippier rubber.

Tires 101 by Noah Bodman for Blister Gear Review.

Maxxis Triple Compound

Rubber’s hardness is quantified as its durometer. There are a few different durometer scales, but bike tires are usually measured using the “a” scale, so you’ll sometimes see a bike tire’s “stickiness” referred to as a number with an “a” after it. A 60a tire is a medium-hard compound that should last a relatively long time and roll fairly quickly. A 40a tire is quite soft, and will give great grip at the cost of rolling resistance and durability. While not all companies will specify the durometer of their tires, most fall somewhere in the 40a to 70a ballpark.

A tire’s durometer isn’t the full story though — there are all kinds of additives that are put into the rubber that can make it behave differently. Companies use varying amounts of carbon black, silica, graphene, and an assortment of other materials to help improve the rubber’s durability, grip, or rolling resistance.

Most of the companies have a variety of marketing terms for their rubber compounds. Here’s a rundown of the most common ones with some quick descriptions:

Bontrager

Bontrager doesn’t have any special names for their compounds, but it’s not too hard to find the durometers of many of their tires. Their XC tires tend to be 62a for faster rolling. Some of the trail and enduro use dual compounds (61a in the center for fast rolling, 51a on the sides for grip). Their DH tires are usually a bit softer.

Continental

  • Basic / Single – Continental doesn’t provide any information on their single compound tires, but guesstimates place them at the harder end of the spectrum – around 60a.
  • PureGrip – Again, Continental doesn’t provide a whole lot of information about the compound. It’s grippier than their basic single compound tires, but not as grippy as their BlackChili compound.
  • BlackChili – Unlike most other companies, Continental’s BlackChili compound is a single rubber compound that has some additives to improve tire life and rolling resistance, while at the same time preserving grip. I’d put in the same neighborhood as other companies’ trail oriented compounds (e.g. Maxxis 3C Maxx Terra, or Schwalbe TrailStar), but slightly slower rolling and marginally better durability.

Hutchinson

  • RR XC – a harder compound is used for the base of the knobs, capped with a medium compound for traction, and a softer compound on the side knobs for added cornering grip. The priority is faster rolling.
  • RR END – a harder compound is used for the base of the knobs, capped with a medium-soft compound for traction, and a softer compound on the side knobs for added cornering grip. This is an all-around compound that hits a middle ground on rolling resistance, longevity, and grip.
  • RR DH – a dual compound tire with medium compound knobs in the middle and softer compound knobs on the sides to increase grip.

Kenda

  • L3R Pro – a single, medium hard 60a compound for fast rolling while retaining decent grip.
  • Stick-E – a single, medium soft (50a) compound for good all around grip.
  • RSR – the race version of the Stick-E compound that’s even softer (42a) and grippier.
  • DTC – a dual compound that uses the L3R Pro (60a) in the middle, and the softer Stick-E compound
  • (50a) on the side knobs for good grip while preserving some durability and fast rolling.
  • DH DTC – A downhill oriented dual compound. Medium-soft rubber in the middle (50a) and extra-soft rubber on the side knobs (42a). Priority is on grip, while preserving some durability.
  • R3C – prioritizes fast rolling. Appears to be a triple compound with the base knobs built out of a very hard compound and capped with a hard compound in the middle and a medium compound on the side knobs.

Maxxis

  • Single – a single compound throughout the tread. Usually a medium-hard compound.
  • Dual – medium/hard compound on the center knobs with softer side knobs for better cornering grip.
  • SuperTacky – a super soft, slow rebounding rubber that maximizes grip.
  • 3C Maxx Speed – a harder compound is used for the base of the knobs. The center knobs are capped with a medium-hard compound rubber, and the side knobs use a medium compound rubber. This compound prioritizes low rolling resistance.
  • 3C Maxx Terra – a harder compound is used for the base of the knobs. The center knobs are capped with a medium compound rubber, and the side knobs use a medium-soft compound rubber. This compound prioritizes all-around performance, and hits a middle ground on rolling resistance, longevity, and grip.
  • 3C Maxx Grip – a harder compound is used for the base of the knobs. The center knobs are capped with a soft compound rubber, and the side knobs use an extra soft compound rubber. This compound prioritizes grip and traction over longevity and fast rolling.

Michelin

  • Magi-X – dual compound, with a softer, grippier rubber.
  • Gum-X – single compound that’s on the harder end of the spectrum.
  • Gum-X2D – a harder compound is used for the base of the knobs, capped with a softer compound for traction.
  • Gum-X3D – a harder compound is used for the base of the knobs, capped with a softer compound for traction, and an even softer compound on the side knobs for added cornering grip.

Schwalbe

  • Dual Compound – a medium-hard rubber compound in the middle and a medium soft compound on the side knobs.
  • PaceStar – a harder compound is used for the base of the knobs. The center knobs are capped with a medium compound rubber, and the side knobs use a medium-soft compound rubber. The priority is fast rolling.
  • TrailStar – a harder compound is used for the base of the knobs. The center knobs are capped with a medium-soft compound rubber, and the side knobs use a soft compound rubber. This is an all around compound that hits a middle ground on rolling resistance, longevity, and grip.
  • VertStar – a harder compound is used for the base of the knobs. The center knobs are capped with a soft compound rubber, and the side knobs use an extra soft compound rubber. This prioritizes grip and traction over longevity and fast rolling.
  • GateStar – a harder compound is used for the base of the knobs. The center knobs are capped with a medium compound rubber, and the side knobs use an extra soft compound rubber. This is designed for four-cross racing, with fast center knobs and max grip in corners.
  • Addix Speed – the new replacement for PaceStar – a harder compound that prioritizes fast rolling.
  • Addix SpeedGrip – a new compound developed for all around trail use that balances grip with low rolling resistance and longevity.
  • Addix Soft – as the name implies, a softer compound that prioritizes grip while still trying to retain a bit of durability.
  • Addix UltraSoft – prioritizing grip above all else. Super soft and slow rebounding.

Specialized

  • Gripton – Specialized uses this compound on a bunch of different tires, and it appears that the compound varies a bit depending on the application, so it’s not always clear what exactly this compound designation means.
  • Numbered Durometers – on a many of their tires, Specialized is really good about stating what the durometer is. Sometimes it’s a single durometer, sometimes it’s a dual durometer.

Vittoria

Vittoria doesn’t have specific names for its different compounds, but it does have two tricks up its sleeve:

  • G+ Isotech – this is Vittoria’s catch all phrase for their rubber compounds that they’ve incorporated Graphene into, which (according to Vittoria) allows the rubber to behave both as a softer and harder compound as conditions require.
  • 4C – a 4 compound mix. The base of the knobs are made of a harder compound in the middle, and a slightly softer compound on the sides. Those bases are then capped with a medium compound in the middle, and a softer compound on the sides.

WTB

  • DNA – a 60a durometer, harder compound throughout for fast rolling and longevity.
  • Dual DNA – a harder rubber compound in the middle, with softer side knobs to improve cornering performance.
  • Gravity DNA – the base of the knobs are built with harder 60a rubber, and then capped with a soft 45a rubber to improve grip.

A Side Note on Front vs. Rear

Like with tire width and tread pattern, some people will run a softer compound tire in the front. Front tires don’t tend to wear out as quickly, so the durability issues that come with a soft compound are somewhat negated. And the softer compound will increase traction for the front wheel where it matters most.

Bead Type

The bead of the tire is the stiffer bulge that helps lock the tire on the rim, and there’s basically two varieties: folding beads, and wire beads.

Folding beads (also sometimes called aramid or Kevlar beads) use flexible strands of aramid fiber or some other similar material. They’re lighter than wire beads, and the tire can be folded on itself relatively easily. The vast majority of higher end tires use a folding bead.

Wire beads are heavier and stiffer because they’re made out of steel wires running the length of the bead. You’ll generally find wire beads on less expensive tires, but you’ll also find it on many downhill tires. The stiffer bead can help make the tire more secure on the rim, so in applications where the weight penalty of a wire bead isn’t as significant (i.e. downhill), a wire bead tire can be a good option.

NEXT: Pulling It All Together: Scenarios & Recommendations

10 Comments

  1. Blister Member
    Dan June 23, 2017 Reply

    Noah, great review.

    Any comment on the Maxxis Rekon 2.8? I know you are not a plus bike fan in general. But I love my Pivot Switchblade setup plus, and am still debating the best tires for all around riding in Park City (almost always dry trails, mostly smooth dirt riding with some decent downhill trails). I blew out my stock Rekon in the back after about 10 rides, ripped through the sidewall. Now I have a DHRII 2.8 (it was all the shop had at the time) in the back and stock Rekon in the front. It sort of feels mismatched with the meaty tire in the rear.

    Get a DHF upfront? Switch back to Rekons front and back as a good all-arounder for PC? What would Noah do (WWND)?

    • Noah June 23, 2017 Reply

      Hey Dan,

      I’ve spent a bit of time on the 2.8 Rekon, but probably not enough to make a super confident assessment. But given the tires that you have, personally, I’d just switch them – put the Rekon on the rear and the DHRII on the front. That way you’ll get the meaty traction up where you want it, and the slightly looser feeling Rekon in the back where a bit of skittering about isn’t a big deal. Then, if you slice up the Rekon again (which seems somewhat likely – those things are a little too thin I think), then you could get a DHF to put up front and stick the DHRII back on the rear.

      I suppose that involves lots of swapping tires around, but that’s not too big of a deal.

  2. Blister Member
    Jeff C June 24, 2017 Reply

    Great article! Love when you guys get into the details even if some of them are fundamental. From company to company there seem to be a dizzying array of terminology and special tech that each offers and often times, reviews and comparisons really don’t answer the question. FWIW, I’m one of those guys that had to buy about a dozen different tires and went through the trouble of swapping them out after about 6 rides on each. I ride a Niner SIR9 so its nothing downhill worthy or bad ass but its what I’ve got and does what I need it to do. I followed the hype for a while and even tried a DHF 2.5 up front. Awesome going downhill and it looked cool but pretty much everywhere else it was a lot of work. My favorite combo turned out to be a High Roller 2 up front and an Ikon 2.35 rear. Been loving that pair for the last 2 yrs and have yet to find a strong enough reason to change it. Compromise? Yes. But I’ve got one bike to do it all and these tires seem to get 90% of it done. Keep up the great work!!

  3. Blister Member
    Tod June 30, 2017 Reply

    Thanks for this great overview on mtn bike tires. Very helpful as it is so confusing. Keep up the awesome mtn bike related reviews!

  4. Free July 26, 2017 Reply

    Really amazing article!!!

    Have you ridden the vittoria morsa?
    I would appreciate it if you could share your experience.

    How does it compare to aggressor?

  5. Neil B August 27, 2017 Reply

    Hey Noah ,

    Thanks for the informative reviews. I like them a lot. Proper rider opinion is so useful – there’s a lot of gear out there!
    Tyres especially so this o e is much appreciated.
    I’m a Maxxis DHRII fan too. (And a Mojo Geometron owner. Very long slack and low, used as a UK trail bike).
    Do I remember right that in an early review you made some recommendations about trimming the width of the wider DHRII center knobs to open up the channel?
    I can’t find that article of yours in a search, frustratingly
    Any chance you could link to it please?
    And what tool to use? Plain sidecutters perhaps.

    MAYBE I dreamed it ‘;~}.

    Thanks lots.

    • NeilB August 27, 2017 Reply

      Aha,

      Found it.
      Needed to search “DHR2” not “DHRII”!

      It was Kevin’s article from the launch.
      http://blistergearreview.com/gear-reviews/maxxis-minion-dhr2

      What do you think about cutting the DHRII to increase corner grip for use as a front Noah?

      Thanks
      Neil

      • Noah Bodman Author
        Noah Bodman August 28, 2017 Reply

        Hey Neil,

        Personally, I don’t spend much time cutting tires, but that’s mostly a laziness thing. I’m with Kevin though – trimming a bit off the center knobs of the DHRII would increase cornering grip a bit, and would still probably preserve most of the DHRII’s fantastic braking abilities. I’ve run an uncut DHRII in the front on a few occasions and I like it, although I like the DHF better for the front (because it corners a bit harder). Also consider a Bontrager G5 – they run a little bigger than the Maxxis tires, but the tread pattern isn’t too different than what you’d get with a cut DHRII.

  6. neilB August 29, 2017 Reply

    Hi Noah,
    great to know, thanks for the reply.
    as well as being hard work, cutting is risky too, it would be just like me to get it wrong ‘;~}, it WAS great to read about Kevins experiments though. Helps in understanding treads.
    That G5 sounds like it would make one great alpine uplift tyre
    Thats one good write up from Kevin: http://blistergearreview.com/gear-reviews/bontrager-g5/2
    Shame Trek don’t do a trail-bike weight version. Even the 2.35 seems a bit of a “man-up weight” for “pedal up” sessions.
    My next non mud front’ll likely be your recommended DHF in WT on a DT471 or even a 35 internal rim. Maxxgrip maybe even.

    I do like the Mavic Claw though (on a 34 internal rim), maybe you’ll get to try one of those.
    Gwin’s signature Onza Aquila certainly looks an interesting project, not least inasmuch as he lined up the centre and sideknobs.
    Maybe he can ride like that on pretty much any tire though ‘;~}

  7. neilB August 29, 2017 Reply

    MM,
    I see that for “Enduro” there is the Bontrager SE5 Team Issue though.
    It’s based on the G5 apparently.
    shame they made it of harder rubber (if it was going on the front) might make an OK rear for trail bike use I guess.
    N

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