Changing Tyres

From Honda Trail Bike Wiki

With thanks to Neduro on ADVRider, I've copied his thread on tyre changing [1]here to the Wiki.

These pictures happen to have been taken changing dirt tyres, but the techniques shown here apply equally to street tyres (well, maybe not the bits about rim locks and tube positioning).

Tyre changes are not difficult. In putting together this set of directions, I changed both tyres on my KTM at an unhurried pace, including shooting 72 pictures which took lots of time to pose, and including cleaning and greasing axles, checking brake pads, and validating spoke tension, in 54 minutes from first picture to last. I never used more than moderate force, did not break a sweat, and no curses were uttered.

A few things to have in mind as you approach this project. 1) If you are using force, you are doing it wrong. You are not stronger than the tire bead, and you don't want to be (broken beads mean wasted tyre). If things are not happening easily, THINK about what forces you are putting on the tyre and reposition things to align those forces with what you are trying to do. Like most things, tyre changes are more a mental exercise than a physical one. 2) The devil, as they say, is in the details. A small change in position etc can make all the difference. Pay attention to the subtleties of what you are doing. The single most important thing to notice is that the profile of the rim has a dish, or a low point, at the centre where the spokes join. This dish is your friend - if the bead of the tyre is resting down in the dish, it will be loose on the opposite side. If not, not even a 50 HP dirt bike can break it free. 3) Always look at the side of the tyre opposite where you are working. All of the tension that you are working around is generated over there, not at the point where the tyre lever is contacting the tyre.

Again, these same approaches will apply to street tires as well, but I'll just focus on the pictures I have for now and worry about the others later.

Tyre Removal:

We'll assume, for a moment, that you are able to get your bike situated so that the wheel in question is free, and are able to remove it, and so we'll start with the wheel off the bike and go from there.

I like to change tyres using the new (or old) tyre as a rest for the work I'm doing. The primary reason for doing so is to keep the sprockets and brake discs off the floor and unbent. Lots of companies make nifty stands, but I've never been able to justify one given how well another tyre works.

Step 1: Let air out. Remove the valve stem all the way, so that the tube can 'breathe' as you change the volume of the tyre through your manipulations. Tip: loosen the valve stem nut, if you have one, prior to letting the air out.

Step 2: Loosen (but do not remove) the Rim Lock. Once the nut is loose, push the stem in to make sure that the rim lock has released its grip on the tyre carcass. You may need to hit the stem with your socket hammer that you used to loosen the nut to get it to let go.

Step 3: Break the bead. On dirt tyres, this is no big deal - I'm doing it here with my chaco'd foot. I can also do it by hand, if I feel like getting dirty. This is the biggest difference for street tyres! We'll get to that later. If you're feeling uppity, turn the tyre over and break the other side right now too, but chances are good that it doesn't really matter, that it will come free during your other manipulations anyway.

Step 4: Insert 2 tyre levers, 4-6" apart, 90 degrees off the valve stem and/or rim lock. You don't want to go opposite the stem or rim lock because then the bead can't seat all the way into the dish of the rim. You don't want to be anywhere close to them because they will make it harder to get the bead out. So, split the difference.

Step 5: Start working around tyre away from initial "bite", inserting tyre levers close at first and farther as the bead gets looser. Tip: if the tyre is making it difficult to get the lever inside the bead, insert the tyre lever just out from where the bead is crossing from outside to inside. It will be a very small bite, but it will be easy to get the lever in.

Step 6: Continue to work all the way around the tyre until one whole side is off. Step on the middle of the rim and pull the tube out, taking care to ease the valve stem out through the hole in the rim.

Step 7: Flip rim and tyre up to vertical, and insert tyre lever as shown to pull second side toward the same as the first. Use the other lever to pull the bead off. Once you get about 1/4 of the way around, you should be able to simply jerk the rim out of the tyre

Image:TyreChange10jpg

A few words before we get started on installing the new rubber.

Your primary task in installing a new tyre is protecting the tube from damage. You want to make sure the tube is lying straight throughout the tyre, so that it won't chafe on itself and cause a flat. You want to make sure not to damage the tube with the end of your tyre lever. You want to make sure that the valve stem is nicely aligned with the hole in the rim, so that it doesn't rip the stem from the tube upon shifting.

As above, if doing the rear wheel, it is nice to work on the side opposite the sprocket. Plan accordingly.

I do not use any soap or water - I prefer the tyre to be a little sticky, so that it holds position as I work on it. Others disagree with me. Experiment and make up your own mind.

Step 1: install the valve stem and add some air to the tube. The goal is to give the tube enough body to roll itself out of the way of the tyre lever etc, without making it hard to get the bead into the dish of the rim. Another important function of adding air before you start is that it will ensure the tube lies flat, with no twists or kinks, inside the tyre.

You will be hard pressed to flat the tube with your tyre lever if you have added some air first.

Step 2: Install the tube in the tyre (I cheated here and put the tube in the tyre before adding air).

Step 3: Align tyre/tube combo with rim/rimlock combo, so that valve stem is ready to pass through the hole.

Step 4: If the valve stem and rimlock are in the same quadrant of the wheel, you've got it easy, because you can pass the valve stem through the hole in the rim, and align the rim-lock all at the same time.

If they are opposite, just worry about aligning the rim-lock for now. I'll show pics of how to deal with the valve stem in a moment.

Aligning the rim-lock - you want to push the rim-lock down, so that it is between both beads of the tyre and when the time comes, can suck the beads up and into the rim as it is designed to do. Trust me - if the rim-lock is not inside the beads, you will not pass go, and you will not collect £200 no matter how hard you try.

Here the valve stem has passed through:

And here the rim-lock has been pushed between the beads and the tyre is ready to be pulled on.

Step 5: Pull the first side of the tyre down onto the rim, taking care as always to keep the bead in the dish of the rim.

If you could not slide the valve stem in at the outset, here's where you do so:

Note that the valve stem is aligned with the hole it will pass through.

This picture sucks, but all I'm doing is shoving the valve stem inside the tyre.

And this picture sucks too, but I'm lifting up the tyre from the opposite side (the one that is already on) so that I can move the valve stem into the hole.

So, now we've got one side of the tyre on, the valve stem and rim lock positioned correctly, and the second side completely off. We're in the home stretch.

Step 6: The second side of the tyre. You want to start with the portion of the tyre immediately adjacent to the valve stem, so that the bead of the tyre won't trap the tube adjacent to the valve stem.

From there, you want to work the shortest route toward the rim-lock. If the rim-lock and valve stem are exactly opposite each other, whichever direction will be fine.

And finally, you want to finish the tyre off 90 degrees from the valve stem and rim-lock, so that they are not in the way of getting the bead into the dish of the rim. As always, take care that the opposite bead is down in the dish:

Step 7: Air the tire up. Always fill tubes slowly - not from a 120 psi compressor that's all charged up. Filling the tube too quickly can result in a twist that does not resolve itself. Bicycle floor pumps are best, but if you must use a compressor (I do), just switch it off once it hits 40 psi or so.

Step 8: Tighten the rim-lock - this should always be done after adding air to the tyre, so that the tube has no chance of being caught between the rim-lock and the tiye bead, AND so that the tyre has the best chance to seat evenly.

Done!