The Ultimate Guide To Tyres And Tubes

Dirt bike tyres play an integral role as they're the only contact point between your bike and the terrain your riding. MX tyres and enduro tyres come in different sizes, treads and compounds, and they alter the handling characteristics of your bike on particular surfaces. There's a lot to understand about dirt bike tyres, and we cover the ins and outs in this ultimate guide.

Understanding tyre sizes:

Dirt bike tyres come in many different sizes that come down to width, height and diameter. Most dirt bikes that are 125cc and up will have a 21-inch front wheel and 19-inch rear wheel, while some off-road or enduro models will be fitted with an 18-inch rear wheel.

Aside from the diameter of your rim and tyre, the key difference in tyre sizes is the width and wall height. Typically a 125cc will run a narrower and shorter tyre than that of a 250cc, while a 450cc will run an even larger tyre in both width and height than a 250cc. These sizes are determined by a sequence of numbers.

The first number gives you the width, followed by the wall height and the diameter. Here's an example: 110/90-19

The '110' refers to the width of the tyre in millimetres, as does the '90' - which refers to the wall height as a percentage of the width of the tyre. The '19' refers to the diameter of the rim that the tyre suits in an inch measurement. Here are some common variations:

• 100/90-19
• 130/90-18
• 80/90-21
• 120/90-19

An 18-inch wheel typically has a taller wall height, the taller the tyre wall means the more the tyre can flex and roll which lowers performance through corners. Contrary to this, the added flex gives a smoother, more controlled ride over tree roots and rocks which you encounter more on enduro.

Wider tyres make the bike harder to turn, the wider the footprint the more it will want to stay upright which can cause a 'front end push' feeling through turns. Also for soft terrain or rutted tracks, a wider tyre will struggle to fit into ruts easily which will affect your performance.

A wide tyre comes into its own on hardpack dry conditions, where a wider footprint means more grip providing the tread pattern and tyre rubber compound are suited.

No matter what bike you have it should have the wheel sizing written on its tyres to identify what you have. Then its a matter of narrow down the tyre you need by thinking about what type of terrain you ride on most.

It's important to choose the right sized tyre recommended for your particular bike - if you decide to run a wider than normal tyre on a narrow rim, the performance of the tyre will be compromised as the shape of the tyre carcass will have been changed as it is manipulated to fit onto the odd size of the rim. The same applies if you put a narrow tyre on a wide rim it will push the tyre wall out and change the tyres’ footprint which will impact performance and grip.

How to choose the right tread pattern of motocross tyre:

I'm riding sand, what tyre do I need?

If you’re riding some of the best sand conditions Australia has to offer, then a dedicated sand tyre is a must. Sand specific tyres feature a 'paddle' tread pattern on the rear that propels you forward in deep sand while also maintaining tracking in a straight line.

Sand front tyres often feature a skinny and tall tread pattern to easily navigate the soft conditions, however, some riders will use a sand tyre on the rear and an intermediate on the front.

Popular rear sand 'paddle tyres' include the Pirelli Scorpion MX soft, Dunlop Geomax MX12, Bridgestone Battlecross X10 and Michelin Starcross 5 sand to name a few.

I'm riding hard-packed dirt, what tyre do I need?

Tyre selection is pivotal when it comes riding hard-packed tracks and trails, as the surface is one of the most difficult to navigate. Hard-packed tyres are generally softer in compound, with a greater amount of shorter knobbies.

Most hard-packed Australian motocross tracks are prepared on the loamier side on race day, so riders will almost always use an intermediate MX tyre. Enduro and off-road riders will often have a hard-packed tyre fitted to their bike when riding in such conditions, as the tyre is designed to handle tough ground, rocks and basically anything that can be thrown at it.

If this sounds like the type of track or trail you’ll be racing at, then look at the front and rear ranges that include the Michelin Starcross 5 hard and Bridgestone Battlecross X40 hard.

I always ride a mix of tracks surfaces, what should I get?

If you're riding recreationally, or simply hitting up different tracks every weekend, then an intermediate front and rear tyre is the perfect balance of performance, durability and cost-effectiveness. You won’t pigeon-hole yourself to riding on a certain surface with an intermediate (you'll destroy a sand tyre in a matter of laps if you use it on hard-packed surface), so it will serve you well in sand, loam, and hard-packed conditions.

Tyres that will provide great value and performance include the Bridgestone Battlecross X30, Pirelli Scorpion MX Extra X, Dunlop MX52 and Michelin Starcross 5 medium.

How to change a dirt bike tyre:

First things first, you’ll want to have to right tools for the job when you’re changing your dirt bike tyre. You’ll need at least:

• Large ring spanner or ratchet wrench for rear axle
• Smaller (approx 12mm) spanner for rim lock
• 2x Tyre Levers or Tyre Spoons
• Tyre pressure gauge + tyre pump
• Wire Brush

These tools will also make the task easier:

• Bead Buddy
• Valve Core Remover
• Ballard's Dirt Bike Tyre changer

Tip: Leave the tyres in the sun for an hour or two before installing them as this will make the rubber easier to work with. The first step involves removing the wheel from your dirt followed by undoing the rim lock and removing the valve core - this will make it easier to remove and refit the tube (and it also reduces the chances of pinching it!)

When the tyre is deflated, make sure the bead has been popped on both sides of the tyre. It's now time to use your tyre levers to pull one side of the tyre off the rim - use the pointy end of your levers, and take small 'bites' as you work your way around the rim.

If it becomes hard to pull the lever over, ensure that the bead on the opposite side of the tyre is still pushed into the rim.

Now you'll want to lift the side of the tyre up and remove the old tube before putting a tyre lever in the opposite side of the tyre to start popping the bead off on that side of the rim. It's the same process of taking small bites as you work your way around the rim with the tyre levers.

Once you've removed the tyre, it's time to install your fresh rubber and tubes.

The first step in installing your new tyre is to place the rim lock inside the tyre, which will be your starting point for the first side. Work your way around the tyre with a lever.

Tip: Use a lubricant on the bead to make the job easier if required.

When the first side of the tyre is on, install the tube. It's a good idea to install the tube when it has some shape, so it's best the inflate and deflate it before installing. Start at the valve core and line it up with the hole in the rim, and once this is through, feed the rest of the tube around.

Next up is fitting the other side of the tyre!

Use two tyre leavers and start opposite the rim lock, and start with larger bites this time as you move around the rim. You might need to hold one tyre lever in place to keep the bead well inside the rim.

If you finish opposite the rim lock, you'll likely finish at the rim lock - make sure the final section of bead that you push up towards the rim lock before popping the last bit of bead over the rim to prevent it getting trapped and not seating on the rim.

After the tyre has been fitted, ensure you reinstall the valve core before inflating thedirt bike tube - inflate the tube until the bead as seated accordingly. Now you can adjust the tyre pressure to suit, as well as tightening the rim lock and reinstalling the valve cap.

When should I replace my tyres?

Like anything, dirt bike tyres have a shelf life, which is around four years from manufacture - but if you are riding regularly this will be much quicker! Replacing your tyres come down to two things: Rounded or torn knobs, and cracking or discoloured tyres.

Rounded or missing knobs is the easiest indicator that your tyres need to be replaced.

Dirt bike tyres are going to start wearing down and rounding as soon as you hit the dirt, although when a tyre has reached the point of replacement, it's generally significantly lost its sharp edge - essentially, it will look worn down and lifeless.

Torn and missing knobs, which usually occur on the rear tyre, is an indicator your tyre needs to be replaced immediately. This typically comes as a result of old and hard rubber, or the type of dirt your riding on (such as hard-packed terrain!). Discoloured or cracking tyres is another sign your tyres need to be replaced as soon as possible, and this usually happens through old age or poor storage.

Cracking can appear at the base of the knobs around the tyre, and is usually more apparent on the sidewalls of the tyre, while a discoloured tyre will generally look quite faded and grey in colour.

You can learn more on replacing your dirt bike tyres in this guide: When Should You Replace Your Tyres.

What tyre pressures should I be running?

Tyre pressures come down to the terrain you're riding and personal preference. Most motocross and enduro tyres run air pressures between 10-20psi, although a popular go-to pressure is 14psi, which offers adequate grip, yet it isn't too low that you'll suffer a puncture.

The more pressure in your tyre, the less grip you'll have, while the least amount of pressure in your tyre will provide a spongey feeling and could potentially roll on the rim in corners, impacting performance and potentially causing damage.

Issues you might encounter with the incorrect tyre pressure:

• Tube or tyre failure, punctures
• Cause uneven tyre wear
• Under inflation can cause the tyre to come off the bead

Do new motocross tyres have a break-in period?

There is no break-in period for new motocross tyres, however we do suggest easing into riding on a fresh set of rubber, especially if you have changed size, tread, brand or rubber compound. Get a feel for your new rubber to work out how well they hang on before you go full throttle into a corner, or you may end up on the ground before you have even worked up a sweat!

What's the difference between regular tubes, mousse tubes and tubeless systems?

Regular tubes are the most common type of tubes on dirt bikes, and they are what will come fitted as standard on your bike.

Regular tubes are typically still used by motocross riders, as they're affordable and relatively reliable on a motocross track.

Mousse tubes are really common amongst enduro and off-road riders, and they are sometimes used by motocross riders to prevent suffering flat tyres (it's team protocol for CDR Yamaha riders to use mousse tubes in motocross!)

A mousse tube is essentially a thick foam tube that replaces a regular tube, maintaining a steady pressure without air while being unable to suffer a puncture. They tend to offer a different feeling initially, and they are usually more difficult to install if you haven’t done it before.

A tubeless system, offered by Nuetech, eliminates the use of a traditional tube by creating a high-pressure rim lock and seal that secures the tyre bead to rim. This is a system that some off-road and enduro riders use, as tyre pressures can be reduced significantly over regular and mousse tubes.

Check out the massive range of Dirt Bike Tyres at MXstore:

• Bridgestone Dirt Bike Tyres
• Dunlop Dirt Bike Tyres
• IRC Dirt Bike Tyres
• Michelin Dirt Bike Tyres
• Motoz Dirt Bike Tyres
• Pirelli Dirt Bike Tyres

If you have any further questions regarding tyre selection don’t hesitate to contact the friendly MXstore team