A tire that slips on a banked turn, a cut casing after a rocky section, or worn tires before a big day at the bike park: knowing how to change mountain bike tires prevents you from losing a ride to a task that primarily requires a methodical approach. On the dry, steep, and rocky trails of the Val de Bagnes, proper tire mounting is just as important as choosing the right model. A poorly positioned tire, a pinched bead, or missing sealant can quickly become costly.
Changing a tire isn't complicated, but the procedure varies depending on your setup: inner tube, tubeless, or tubeless with inserts. Before you begin, identify what you have on your wheels and allow yourself some time. Most problems arise from rushing, not from a lack of strength.
Before changing your mountain bike tires: check compatibility and wear
A new tire must fit your rim, your riding style, and the clearance available on your frame or fork. The size is marked on the sidewall, for example, 29 x 2.40 or 27,5 x 2.50. Also check the ETRTO standard, expressed in millimeters, which is particularly useful for avoiding confusion between similar sizes.
Width isn't just about comfort. A tire that's too narrow on a wide rim will feel square and lack progressive handling when cornering. Conversely, a tire that's too wide can become imprecise, rub in mud, or lack support at low pressure. For an enduro or bike park mountain bike, volume and casing are just as important as the advertised width.
Next, check the direction of rotation. An arrow and the word "rotation" are usually marked on the sidewall. On some front tires, the wrong direction reduces braking grip and mud evacuation. On a rear tire, it can also negatively impact performance. Some tread patterns are reversible, but don't attempt it yourself: follow the manufacturer's instructions.
It's wise to replace a front tire before its treads are completely worn down. The front tire provides steering and braking grip. At the rear, moderate wear can be acceptable if you're trying to save a tire, but excessively smooth rubber will cause slippage during acceleration and on technical climbs. A visible cut in the casing or exposed threads necessitate replacement.
The equipment needed to change mountain bike tires
Prepare your workspace. A clean wheel makes it easier to spot a rim crack, a stuck thorn, or damaged tubeless tape. For most setups, you'll need a floor pump, two plastic tire levers, a rag, and possibly soapy water. Avoid metal tire levers: they can mark the rim, damage the tape, or ruin a carbon bead.
For tubeless setups, add suitable sealant, a valve core removal tool, a syringe or small dosing bottle, and ideally a pump with an air reservoir or a compressor. If your bike uses an insert, also get compatible valves. Their side vent prevents the insert from blocking airflow.
Do not mount a new tire on a rim that has a dent, a crack, or a loose rim tape. With an inner tube, the risk is an immediate puncture. With tubeless tires, the seal will be unreliable, and the tire may lose pressure for no apparent reason.
Remove the old tire without damaging the wheel
Place the wheel flat or on a work stand. Deflate it completely. On a tubeless setup, remove the valve core to speed up deflation and prevent sealant from spraying out. Then, press both tire beads towards the center of the rim all the way around. This step is crucial: the central area of the rim is more concave and provides the necessary clearance to remove the bead.
Start on the opposite side of the rim from the valve. Using your thumbs, first try to push the bead over the rim edge. If it resists, insert a tire lever, hook it onto a spoke if necessary, and then proceed gradually. Do not pull abruptly on any one area. On a tight tubeless setup, work the bead around the entire wheel before forcing it.
Once a bead is removed, take out the inner tube if there is one. For tubeless tires, carefully remove the tire and wipe off any old sealant. Take this opportunity to inspect the inside: thorns, metal fragments, and small stone chips often remain in the casing. If you are keeping the tire, remove these debris before making any repairs.
Mounting a tire with an inner tube
First, install one bead of the new tire. Observe the direction of rotation and, if possible, align the logo with the valve. This detail helps to quickly locate a puncture on the tire compared to the inner tube.
Inflate the inner tube slightly, just enough to give it its shape. Insert the valve through the rim hole, tighten the nut a few turns, then place the inner tube inside the tire without twisting it. Install the second bead, starting at the valve and finishing at the opposite end. Always keep the already installed sections in the center groove of the rim: this is the step that makes those last few centimeters possible.
Before inflating, run a pinch tape around the rim. Make sure the inner tube doesn't protrude anywhere between the bead and the rim. Inflate gradually, then check the wear indicator line molded onto the sidewall. It should be evenly spaced from the rim all the way around. If it isn't, deflate the tire, reposition it, and start again.
Mounting a tubeless mountain bike tire correctly
Tubeless tires offer comfort, grip, and better resistance to small punctures, provided the installation is clean. Install the first bead, then insert the rim strip if your wheel has one. The strip adds protection against rim impacts and allows you to run lower tire pressure, but it makes installation more physically demanding. On a challenging ride, this compromise is often worthwhile. For cross-country riding or lightweight tires, it's not always necessary.
Mount the second bead, finishing well away from the valve. At the valve, the bead must remain in the rim bed, not on the thickness of the valve base. Otherwise, the last few centimeters become unnecessarily difficult. If the tire won't go on, use a little soapy water on the bead. Do not use oil or grease: they compromise tire grip and can interfere with sealant.
You can pour the sealant into the tire before fully closing the second bead, or inject it through the valve after removing the valve core. Injecting through the valve is cleaner, especially with a wide tire or an insert. The amount depends on the tire's volume. For a 29 x 2.4, an average dose is usually sufficient, while a 2.6, a downhill tire, or a setup with an insert may require more. Follow the product's recommendations and check the level regularly.
Inflate the tire quickly to seat the beads on the rim hooks. A popping sound is normal. If the air escapes too quickly, check that the beads are close to the rim edges, add a little soapy water, and use a faster air source. Once both beads are in place, rotate and shake the wheel in several directions to distribute the sealant. Then let it sit flat on each side for a few minutes.
Adjust the pressure according to your terrain and riding style
There's no single ideal tire pressure that works for everyone. Your weight and gear, tire width, casing, internal rim width, terrain, and speed all affect the setting. A lighter rider on a wet trail can run significantly lower than a fast rider performing a series of landings in a bike park.
Start with a conservative pressure, then adjust it gradually. If the tire deforms significantly under load, hits the rim, or feels vague, increase the pressure slightly. If it bounces on roots, lacks grip, and tires your hands, reduce it a little. The front tire can often run with less pressure than the rear, as it carries less load and needs to maximize traction.
After the first tubeless inflation, check the pressure the next day. A slight loss can occur with a new setup, but a significant drop often reveals a problem with the valve, tape, bead, or insufficient sealant. It's better to fix it at the shop than at the start of your first climb.
Mistakes that ruin a good edit
The first mistake is forcing the tire bead with an unsuitable tool when it's not seated in the rim groove. The second is neglecting tubeless tire tape: a tiny leak around a spoke is enough to make a tire installation frustrating. Finally, don't forget to check the wheel axle tightness and the correct positioning of the caliper or disc before setting off again.
Always keep a spare inner tube, a cartridge or mini-pump, and a tubeless tire plug in your bag. Sealant will fix many punctures, but not all cuts. On alpine trails, being able to repair your tire yourself is the best way to ensure you finish the day on your bike.
If a tubeless setup is malfunctioning, if a rim has sustained an impact, or if you're unsure which casing to choose, the Backside Verbier workshop can check everything before your next ride. A well-chosen and properly mounted tire doesn't just save time; it allows you to attack corners and rocky sections with the confidence the terrain demands.
