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mountain bike tires: an overview

Shopping for a new tire can be just as overwhelming as exploring new bike options, if not more.  With so many choices how does one choose which tire to spec their bike with and where to put it?

Changing a tire on your bike can drastically change the way it rides.  Whether you’re fighting for grip or going for speed there’s a tire suited for you.  We’ve created a buyer’s guide to help break down the jargon and make it a little easier for the customer to tune their ride.  For this guide, we want to cater to the recreational / every day rider, someone who is looking for that balance between grip and speed.  To break this down let’s establish the different disciplines.

cross country & trail

For this discipline, riders are usually after a few things – reducing weight, increasing rolling speed and improving climbing traction. Examples for this type of tire include the Maxxis Ardent and Ardent Race and the Bontrager XR3.

maxxis ardent

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bontrager xr3

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all-mountain & enduro

In this category, riders are typically looking for more grip/cornering traction and stability. Grip and stability can work hand-in-hand and can come from a number of different factors when designing a tire – the softness of the rubber (durometer), the height of the knobs (center/side) and the tire’s width, etc. Examples include the Maxxis DHF and DHRII (the F and R stand for Front and Rear.) Specialized Butcher, and the Bontrager SE4.

maxxis dhf

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specialized butcher

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bontrager se4

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selection

Picking the right tire is all about creating a balanced combination between the front and rear that caters to your riding style or how you want to ride.  For the most part, riders will spec the front of their bike with a tire that offers more grip and stability while equipping the rear with something that gives good climbing traction and faster rolling speed while maintaining good cornering traction.  This is a good place to start if you’re not racing at either end of the spectrum (cross-country or gravity/downhill).

tread patterns & tire widths

Tread patterns are a huge factor in placing a tire into its respective discipline.  You have your extremes, but you also have tires that meet in the middle.  These patterns can be seen on the Maxxis Aggressor, Specialized Purgatory, and the Bontrager XR4.  For riders who want the best of both -- fast rolling and great cornering/climbing traction -- these will be what you’re shopping for.  However, as this guide is for that every day, recreational rider, we would recommend these as a good option for a rear tire as you see these specifically spec’d on stock bikes in the shop.

As for the front tire, you’ll see bigger knobs and wider tires for both increased traction and stability.  These tires also feature softer rubber compounds that create a tackier ride feel.  Softer rubber is, unfortunately, associated with faster wearing of the tire entirely, which is why you should install these on the front given the rear tire typically wears out quicker. 

A wider tire can give you a more stable feeling, but consider your rim width when shopping for tires 2.5 inches and above.  If you have a thinner internal width (~19-24mm) and you try to stick a 2.5 on it, it can change the tire profile and you may not actually benefit much from the increased width.  Luckily, most of these tires come in different widths, so you can gain that traction and stability without jumping to a wider tire all together. e.g. Maxxis DHF 2.3, Specialized Butcher 2.3, Bontrager XR4/SE4 2.3.

tire casing

A tire’s casing is fabric that acts like a skeletal system beneath the outer rubber and is measured in Threads Per Inch (TPI).  The most common TPI measurements you will see are 60tpi or 120tpi.  

A lower TPI will have a larger thread and function as a stiffer casing while a higher TPI has a smaller thread with less rubber packed between threads, making for a lighter and more supple ride feel.  Note that the lower thread count isn’t going to have the ride quality of the higher TPI, but offers durability against cuts and flats.  

Thus, if you want a high-mileage, durable tire, look for the 60tpi marking; if you want a smoother ride feel and lighter weight, go with the 120tpi.

The number of layers for the casing can change as well. Most  cross-country tires will be made with a single-ply casing, which helps the tire conform well to the terrain and be lightweight.  All-mountain / enduro casings will have a dual-ply casing, providing added protection and stiffness to the sidewalls.

tire compounds

The compound of a tire is refers to the softness of the rubber, expressed as the durometer, and measured in Shore A Hardness.  This measurement is seen as a number (1-100) followed by the letter “a”(48a, 50a, 61a, etc.). The lower the number, the softer the rubber compound. 

When shopping for a tire, though, you’ll see it as an advertised name, e.g. 3C MaxxTerra, GRIPTON.  3C MaxxTerra, MaxxGrip, and MaxxSpeed are good examples of how the compounds can be changed to get the most out of a tire's desirable characteristic.  MaxxTerra will have a pretty neutral durometer.  The base of the rubber is hard but as you get closer to the outer surface it becomes softer. 

Maxxis also makes the side knobs a softer compound and the center a medium compound.  The MaxxGrip and MaxxSpeed are going to have different proportions of this measurement with “Grip” having a thinner layer of hard rubber at the base, leading to a higher proportion of soft/medium compounds, and “Speed” having a thicker layer leaving the softer rubber on the outer surface of the knobs.