In response to a frequent request in the shop, here is our guide to changing a tyre. If you practice and follow this, you'll find it easier and less likely pinch your tube in the process.

We didn't want to burden you with definitions up front so check the end of the article for these.

Step 1. Taking the wheel off the bike

1. open quick release ("QR") skewer.  The words open / close are written on most skewers.  In any event, a closed skewer will curve inward towards the wheel
2. open brake quick release if one is present
3. move rear derailleur rearward to allow cassette (cogs) to slip between upper and lower sections of chain (if rear wheel)
4. unwind skewer to clear "lawyer tabs" (if front wheel)

Step 2. Remove old tyre

1. Let air out of tyre
2. Start with valve at top and tyre resting on ground.  Wheel should be leaning against your knees
3. Using your palms, wiggle the tyre to loosen the tyre's beads from the hook of the rim.  Work your way from the valve downwards to push tyre towards the opposite end of the wheel from the valve, this puts all the slack into one place.
4. Flip wheel up and either squatting or sitting on a stool, face the wheel.  Some tyres will be loose enough at this point to simply pull the tyre off the rim with a bit of effort.  If not, work a tyre lever into the space between a loosened bead and the rim.  Pry a bit of tyre off the rim.  Hook the end of the first tyre lever around a spoke, insert another tyre lever about 5cm further along the bead and repeat.  When enough of the first bead is loosened, a tyre lever will not hook onto a spoke any longer and can simply be rotated along the rim, separating the bead from the rim as it goes.
5. Remove the tube, pulling out the valve last.  You will have to tug the tyre back over the top of the valve to free the tube completely
6. Hold the wheel down to the ground with your toes and with the wheel between your legs pull up on the tyre to start pulling the second bead off the rim.  The tyre will come off on the same side of the wheel as the first bead you loosened. 

Step 3.  Install new tyre

1. If a folding tyre, work it into shape. 
2. Put about 2 tbsp of talcum powder into the tyre and spread it around.
3. Work one bead onto the rim, placing the tyre label at the valve hole
4. Make sure that if the tyre is directional (indicated by an arrow printed on the sidewall) that it is installed the right way!
5. Put enough air into the tube to make it hold it's shape (about 5-10psi)
6. Insert the valve
7. Lay tube into the tyre
8. Pull tyre over the rim all the way around the wheel in a motion which centres the tube on the rim, without actually pulling the second bead over yet.  This puts the tube out of the way of an errant tyre lever
9. Starting at valve hole, pull second bead onto rim.  After wiggling ¼ of the 2^nd bead onto the rim, go back to the valve and push it in to get the thickened part of the tube into the tyre.  Otherwise the tube may get pinched between the bead and the hook of the rim. 
10. Resume working the 2^nd bead onto the rim, with the wheel positioned against your knees and the valve facing up.  Use your palms and wiggle the tyre downwards towards the floor in a motion which forces all slack in the tyre towards the part of the second bead which is not on yet.
11. Flip wheel around so that the part of the tyre which is not all the way on is facing up and out away from your body.  Using your fingertips, pull the remaining bead onto the tyre with a satisfying "look ma, no tools" kerthunk. 
12. If the tyre is too tight to pull on with fingertips alone, either work the tyre from the valve downwards again to get all slack to the point of the tyre which isn't on yet, or use a tyre lever.  Make sure you aren't pinching the tube with the lever.
13. When inflating, pause at 40psi to give the wheel a spin and look for out of round bobbles that could indicate the tyre isn't seated all the way.  If this is happening, let the pressure out and reseat the bead. 

You are done.  With a bit of practice you should be able to do the entire operation in about 2 minutes!

Definitions

Bead

• Tyres have two beads which lock into the "hooks" of the rim.  They may be of lightweight Kevlar (foldable tyre) or steel wire material. 

Casing

• This part of the tyre is comprised of multiple thread layers which wrap around the beads and to which the contact ("tread") surface is vulcanised. 

TPI     

• Threads per inch.  Yes, the imperial system still has a strong grip on tyre manufacture.  Casings with higher thread counts generally yield more supple tyres, improving road feel and handling.

Belts

• Puncture resistant tyres feature dense nylon or aramid (the generic name for Kevlar) layer(s) sandwiched between the casing and the tread. 

Synthetic vs. natural rubber

• When new, a natural rubber tyre will have a waxy look.  Cracking is a result of the wax leaching out of an aging tyre.  Synthetic rubber yields a more durable, higher quality tyre. 

Sidewall

• The part of the casing which is between the tread and the bead.

Tyre orientation

• Directional tyres have an arrow printed on the sidewall

Wheel orientation

• Wheels fit onto a bike this way: QR lever is on the non-drive side (side opposite the gears).  Hubs usually have writing on them.  This should be readable right side up if you were sitting on the bike and wheel was correctly installed.