Mountain Bike Tires 101

Casing and Construction

The casing of the tire is what holds everything together, and there’s a lot of different options out there. This also gets complicated because every company has different names for the features in their casings. This is primarily an issue of weight vs. durability, with grip and ride quality also being secondary factors. There’s a lot of information below, but if you want to cheat the system, just compare the tires’ weights (make sure you’re comparing similar sizes though). Generally speaking, a heavier tire is going to be more durable (this isn’t foolproof, but shortcuts rarely are).

Without getting too far into the weeds, here’s the basic rundown of tire casings.

Threads Per Inch

A key component of any tire casing is a fabric, usually made out of nylon, and that fabric is made up of threads. Just like your bed sheets, threads per inch, or TPI, matter. A low TPI tire will usually have around 60 threads per inch, or sometimes even less. Higher TPI tires will commonly have 120 threads per inch, and some companies are advertising tires with 240+ threads per inch.

Each layer of fabric is called a “ply.” Generally speaking, the higher TPI tires are comprised of multiple plies of lower TPI fabric. Some heavier tires will also use multiple layers of low TPI fabric to increase cut resistance and durability.

The general rule is that a tire with lower TPI fabric will be heavier and more durable. Each “thread” is thicker, and thus stronger. Higher TPI tires tend to be lighter and more supple, but also more prone to damage. The smaller threads are more flexible and allow the tire to conform nicely to rocks and roots, but those thin threads are easier to sever, and tears in the casing tend to happen more frequently.


Most tire lineups start with a basic, single ply tire. The sidewall and casing isn’t reinforced, which means they’re lighter but also more prone to damage. Building off of the single ply tire, almost every company has an assortment of additions or changes that they add in to make the tire more durable, resist punctures, and/or work better for tubeless applications.

Here’s a non-exhaustive list of reinforcements and casing options from some of the major tire manufacturers. For each company, I’ve ordered reinforcements in approximate order from smallest / lightest to burliest / heaviest.


  • Inner Strength – a cut resistant layer in the sidewalls.
  • Core Strength – a 3 piece reinforcement on the sidewalls and under the tread with gaps in between to allow for better tire flex.
  • Dual Ply – a reinforced, 2-ply downhill casing.


  • RaceSport – a lightweight casing with some additional puncture protection.
  • ProTection – a puncture resistant layer wrapping around the entire tire.
  • Apex – extra rubber in the sidewall to help prevent pinches and tears.


  • Spidertech – a lighter weight puncture resistant layer.
  • Hardskin – an edge-to-edge puncture resistant fabric.
  • Hardskin 2×66 – an edge-to-edge puncture resistant fabric, together with 2 66 TPI layers.


  • Tubeless Race (TR) – a lightweight single ply tire that’s designed to be run tubeless.
  • Light Gravity Casing (LGC) – a 120 TPI casing with three additional panels (one under the tread, and one on each sidewall) for puncture protection and a butyl insert near the bead to resist pinch flats.
  • Kenda Sidewall Casing Technology (KSCT) – a 2nd layer of casing material in the sidewalls to resist cuts and pinches.
  • Casing Added Protection (CAP) – a 2 ply bead to bead casing intended to minimize punctures.
  • Downhill Casing (DHC) – a CAP 2 ply casing with the addition of a butyl insert at the bead to minimize pinches.


  • Single Ply – Maxxis doesn’t list this as a feature or reinforcement, so any Maxxis tire that doesn’t have one of their other reinforcements is just a basic single ply.
  • Silkworm – A thin puncture resistant layer under the tread of the tire.
  • Exo – A cut resistant layer on the sidewalls.
  • Butyl Insert – Extra rubber near the bead in the sidewall that helps prevent pinch flats and cuts.
  • Double Down (DD) – a double ply tire that uses two 120 TPI layers.
  • 2-Ply – Primarily used in DH tires; two full 60 TPI layers with additional sidewall protection.


  • RaceShield – a lightweight, 3 x 150 TPI casing, mostly used on XC race tires.
  • CrossShield – a 3 x 110 TPI casing that’s a bit heavier and more robust than the RaceShield.
  • TrailShield – a 3 x 60 TPI casing that’s the burliest of the “Shield” casings.
  • Reinforced – Michelin’s tires that are designated as reinforced have an edge to edge layer to ward off cuts and punctures.


  • Liteskin – the lightest and least durable casing option.
  • Snakeskin – Snakeskin helps with tubeless setup, but it also adds some cut resistance to the sidewalls.
  • Raceguard – extra rubber under the tread to help prevent punctures.
  • Double Defense Performance – A Snakeskin layer with the addition of the Raceguard protection.
  • Apex – A Snakeskin casing with 2 layers of material reinforcing the sidewalls.
  • Supergravity – 4 lightweight plys of material and 2 lightweight plies under the tread.
  • Bikepark Performance – Essentially a low-cost version of Schwalbe’s DH casing with a heavy 2-ply casing, but without some of the additional puncture and tear resistance.
  • Downhill – a heavy 2-ply tire with reinforced sidewalls and puncture protection throughout.


  • 2Bliss – a butyl wrapped bead that makes the tire easier to set up tubeless.
  • Grid – a cut resistant, reinforced layer on the sidewalls.
  • Armadillo – a bead to bead puncture protection.
  • Dual Ply / DH – used on the “DH” designated tires; a 2 ply 60 TPI casing with butyl inserts at the bead to protect against pinches and tears.


  • Rigid – a single ply tire with a wire bead. Mostly designed to be economical.
  • Folding – a single ply, folding bead tire that’s not labeled as tubeless ready.
  • XC TNT – a lighter weight casing that’s still tubeless ready.
  • TNT – TNT (“Tube / No Tube”) is a tubeless ready 120 TPI casing with extra sidewall protection to ward off cuts.
  • AM TNT – the all mountain iteration of the TNT casing, which adds an additional insert at the bottom of the sidewall to help prevent pinches and cuts.
  • rTNT – a heavier 2-ply casing that also includes the same insert near the bead as the AM TNT casing, and uses a wire bead. Generally oriented as a downhill tire.


  • TCS Light – WTB’s basic single-ply tire that’s also tubeless compatible
  • TCS Tough – A full 2-ply casing that still uses a folding bead

Tubeless Designations

Most companies are making many of their tires tubeless compatible. With respect to tubes and tubeless tires, there are essentially four categories: 1) tires that aren’t designated as tubeless compatible; 2) tires that are designated as tubeless compatible with sealant; 3) tires that are tubeless compatible with sealant and also meet UST tire specifications, and 4) tires that are UST tubeless compatible.

Tires that aren’t tubeless compatible. the official position from most companies is that these tires should only be used with tubes. Some sealants can degrade the inside of the tire, and the tire bead is often not tight enough to securely keep the tire on the rim without a tube. And, from experience, some non-tubeless rated tires just won’t ever really seal up, not matter how much sealant you put in them. If a tire doesn’t specify that it’s tubeless compatible, it falls into this category.

There are plenty of non-tubeless compatible tires that I’ve had great luck running tubeless with sealant. There are also plenty that I’ve used that have seeped air, blown off the rim, or otherwise deteriorated quickly. Long story short: if you’re running tubes, non-tubeless rated tires tend to be lighter and cheaper. If you’re running tubeless, it’s probably worth it to just buy a tubeless rated tire.

Tubeless compatible with sealant. This is the most common form of tubeless compatible tire. You’ll need rim tape and sealant (e.g. Stan’s, Cafe Latex, or a home brew sealant — here’s ours) to get the tire to seal up.

Some brands have their own separate designations for tubeless compatibility: Continental = RTR, Maxxis = TR; Schwalbe = Snakeskin; Vittoria = TNT.

UST with Sealant. A couple brands are making tires that are very similar to category #2 (tubeless compatible with sealant), except that the tires meet UST specifications. Essentially, the tire’s bead is a very particular shape that meshes nicely with UST compatible rims, which gives you a better, tighter seal and helps prevent burping. Unlike a full UST tire though, you still need sealant.

The most common example of this is WTB’s TCS (tubeless compatible system).

UST tires. The UST (Universal Standard Tubeless) system has been around for a while, and is airtight without the use of sealant. You need both a UST compatible rim (that is airtight, and has a very specific bead profile) and a UST compatible tire (that has a bead profile to match the rim, and is airtight). With the proliferation of tubeless systems that use sealant, fully UST compatible tires and rims are becoming increasingly rare.

A Side Note on Front vs. Rear

Unlike the size and tread pattern discussion, the issue of casings front and rear doesn’t really have to do with cornering or traction. Rather, it just has to do with the simple fact that the rear tire tends to take more of a beating than the front tire. For that reason, some people will run a heavier, more robust tire in the rear just to help out with flat protection.

NEXT: Rubber Compounds, and Bead Type

10 comments on “Mountain Bike Tires 101”

  1. 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)?

    • 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. 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. 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. 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. 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.

      • 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. 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:
    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. 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.

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