The Ultimate Mountain Bike Tire Guide

January 17, 2009 by  
Filed under Tips

Anyone who has been involved with Mountain Bikes for some time knows that tires can be one of the most confusing and controversial topics.  Some say this tread is faster but others say that.   Some say a softer compound is better here but someone else disagrees.   I’ve talked to a lot of people, rode on a lot of tires and finally I am ready to write THE ULTIMATE TIRE GUIDE!

First I just want to get this out of the way.  The biggest compromise between different tires is that of traction/rolling resistance.  Greater traction generally means a slower but more controllable ride.  Less traction means you will fly off hard terrain but can easily loose control, slide out, or loose traction on loose terrain.

Kevlar or Wire Bead

kenda small block eight mountain bike tires 300x225 The Ultimate Mountain Bike Tire Guide First if you don’t already know there are two types of beads, Kevlar (also called folding) and Wire.  A wire bead means a heavier tire and in general a tire that is more difficult to install and remove.  The first time or two you have to install or remove your Kevlar beaded tire you may be in for a struggle.  They are sized small initially because the beads will stretch slightly over time.  This is by no means the rule as different manufacturers and models of tire will be larger or smaller bead diameters (slightly) but the general rule is Kevlar is lighter and eventually easier to manipulate.

Kevlar Belted Tires

Some MTB tires have Kevlar belts underneath the tread.  This means they have more resistance to thorns and other objects trying to penetrate the tire.  If you are having problems with punctures look for a Kevlar belted tire, it can help.

Tubeless Specific Tires

slime mountain bike tubeless tire sealant 300x300 The Ultimate Mountain Bike Tire Guide Tubeless tires are specifically made for tubeless setups, but you can run them with tubes if you want.  Many standard tires have small holes from manufacturing that will leak if they are ran tubeless (unless you use sealant).  Tubeless tires are made to eliminate these small leaks and usually feature thicker tread and sidewalls.  This is to decrease the chance of a puncture or tear since a tear in a tubeless tire can really screw up your day.  For those of you who do not know the benefits of tubeless, it offers slightly less rotating weight and better traction.  Tubeless tires really hook up with the trail!

Threads per Inch (TPI)

You may have noticed a measurement called TPI when you’re checking out tires at the shop.  The general rule is a greater TPI means a thinner walled tire that will be lighter and have less rolling resistance.  However, these tires will be easier to puncture or tear.

Tread Compound

There are soft compounds, medium compounds and hard compounds.  Kenda has their Stick-e compound that has made them famous.  There is no real measurement that manufacturers do to tell you how soft or hard their tire is.  The easiest way to check is to squeeze a knob between your fingernails and see how much give it has.  Or you can grab a knob and try to move it back and forth.  A softer compound will have more flex.  On the trail a harder compound translates to better energy transfer in optimum conditions.  Kenda has some of the softest compound tires on the market, and because of it, they can be a bit sluggish on hard pack.  But softer compound tires are great for rock, sand, mud, loose dirt and pretty muck everything else besides hard pack.  Choose a tire based on the terrain you will be riding on.  Another thing to note is the size of the knobs will affect their flexibility.  In other words a softer compound tire with big knobs will be stiffer and have better performance on hardpack while a tire with smaller knobs and the same compound will be slower on hard pack but perform better on rock and in the loose stuff. 

Knob Size, Depth. Shape and Spacing

wtb weirwolf mountain bike tire 147x300 The Ultimate Mountain Bike Tire Guide Have you ever seen those sand tires for ATV’s that have the huge scoops for traction?  Think of knobs this way.  A larger knob (both wide and deep) will increase you rolling resistance which means it will be slower on hardpack and faster through loose stuff.  Smaller knobs offer little resistance and fly over tight packed trails but leave you spinning your wheels in mud and sand.  Knob shape also has influence on the tires performance.  Scoop shaped tread means more rolling resistance while squares and round knobs mean a faster tire.  Finally less knobs means less rolling resistance and a faster tire, but you’ll notice that most high performance race tires have lots of tiny knobs.  This is to keep rolling resistance down, but maintain enough traction to keep your bike in control.  Wider spaced knobs can also provide more opportunity for tires to shed mud, but keep in mind less knobs means less traction and poorer performance in loose stuff.

Cornering

I have never heard of anyone who wants a tire with slow cornering.  For the best cornering look for tires with knobs very close to the edges of the tread.  This will help pull you into and through a corner.  And of course harder compound tires will drive you through corners quicker in hard pack while softer compound tires will keep you turning in loose stuff.  The knob size and shape can affect cornering as well.  Larger knobs on the edge offer more traction (rolling resistance) to keep your footing but will be slower than a bunch of small tightly spaced knobs.

Tire Width

The more tire there is on the ground the more traction/rolling resistance you have.  Although there is debate on this. Wider tires put more tire on the ground and give you more traction.  If you want to ride fast on hard pack run 2.0 or 2.1’s.  If you want traction in loose stuff keep going for wider tires until you get what you need.  One of the new trends is to run a wider tire in the front than the rear.  This is to provide better cornering traction and bump absorption.

Pressure

Higher pressures mean that the tire will not have as much contact with the ground.  A tire inflated at a lower pressure will bulge out more under your weight.  This will push a larger amount of tread flat against the ground and yield more traction. Sometimes riders will even deflate their tires slightly when they come upon a section of the trail with a lot of loose rock, sand or mud, then add air when they get back on hard pack.

Tread Direction

Most tires will have a diagram on the sidewall that tells you the tread direction.  In general the knobs will have a pointed side and a scooped side.  Just think the knobs point forward as a good rule of thumb, although some tires are designed to run the opposite direction on the rear wheel or both wheels.

Look at the Big Picture

As you can see there are A LOT of different factors that affect tire performance.  In order to get a good idea of how a tire will perform you need to keep in mind TPI, compound, knob size, knob shape, tread depth, weight, tire width, cornering knobs and the trails you plan to be ridding on.  Ya it’s kind of complicated but when in doubt just ask someone who knows like the guys at your friendly local bike shop (LBS).

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