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
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