This question talks about fitting a tyre back onto a rim, but I'd like to know how to get the tyre off in the first place. Especially if the tyre is very tight, or the dip in the middle of the rim section is very shallow.
Most of my bikes have 406 wheels, and I use Marathon Plus tyres which are quite rigid, so they're really hard to remove without breaking tyre levers or pinching the tube.
What's the best way to get those tyres off the rim so I can fix a puncture?
(I've just realised we don't actually have this question, or any answers!)
Basically the same deal as the question about mounting a tire.
Make sure all the air is out of the tube
If possible, pop just one side of the bead all the way around the wheel. Popping one side only will give the bead more room in the well in the middle of the rim, and thus give you more bead to pull over the top of the rim on the opposite side
Begin to work the bead over the rim with your thumbs or a tire lever. As you work the bead over the lip of the rim on one side it can help to push the tire bead into the well around the opposite side
It can help to start working the bead over close to, but not directly over, the valve stem. Otherwise the valve stem creates a bump in the middle of the well in the center of the rim which takes up some of the slack you need to remove the bead from the rim.
If you're using your thumbs, try to pin the bit of the bead you've worked over the edge of the rim in place with one thumb as you slowly work more of the bead over with the other thumb. It's ok if the opposite bead pops out around the area you're trying to remove.
If you're using tire levers, don't poke a large portion of the lever under the tire as you try to pry it off. Many levers have a small hook on one end that you can attach to a spoke, freeing both hands as you work the next lever under the bead.
At some point you'll get enough of the side of the tire you're trying to remove over the rim that you can slide a finger/lever between the bead and the rim to remove the rest quickly.
The other side should come off with relative ease by hand. If not, remove the tube and follow the same process as with the first bead, prying it off on the same side that you popped the first side off on.
First off, you usually only need to remove one side of the tire if you're just fixing a puncture.
If the tire isn't fully deflated, let all the rest of the air out. It'll make your life easier.
Using your hands, grip the tire near the valve and wiggle it a bit to loosen the bead up from the rim. Work your way around the tire, repeating this process until you get back to the valve. If you've done this and step 1 properly, the tire should be loosely flopping around inside of the rim.
Grab three tire levers. You can do the job with less, but it's harder. I've never needed four. The ones that will get tire off most easily will have a hook one one end, like these:
Insert one tire lever underneath the bead just above the spoke that is most directly opposite of the valve. The tire will be a little looser (more loose?) directly across from the valve and thus, easier to remove. Pry it up and hook the other end of the lever on a spoke.
Check to make sure that you've only got one side of the bead under the lever. If you've got both sides of the bead, the rest will be somewhere between very difficult and impossible.
Repeat step four on the spoke to the right of the one you just hooked, and then the spoke on the left.
At this point, the tire bead may be loose enough that some of the tire levers fall off. If so, great. Pry it the rest of the way off with your finger. If none of the levers has fallen out, it's ok. You just have a tire that fits a bit more tightly. You should still be able to get your finger in just to the outside of your three spokes and slide it along to pry the tire off. As I mentioned before, I have never had to use a fourth lever.
By now, you should have the bead completely removed on one side. You can remove the tube by reaching into the tire opposite of the valve and just pulling it out. You'll reach a point where the valve is the only thing holding it in place. Push the tire out of the way and remove the valve.
If you''d like to completely remove the tire, you'll be able to just yank it off the rest of the way with a firm grip.
The steps above will work on any tire. Skinny, hard case, non-foldable tires tend to be the hardest to get off. Fatties that are foldable can often be removed with nothing more than a good yank. If you have the option, it's still better to do it with tire levers though so you don't risk pulling too hard and damaging the tube. Tires inbetween those ranges tend to vary in difficulty.