Tools: spanner for the axle an some securing bolts, tyre
irons, rag
Extra parts: new tube
Loosen the axle. With a foot under the rear wheel the axle can be pulled out easily - push the wheel a little forward - pick the chain from the sprocket and roll the wheel backwards out of the swing. The bolts that adjust the position of the axle at the rear of the swing should remain untoughed - after assembling the chain will be at the right length again! Don't tough the brakes or the braking pads will be pressed together. Getting them apart again gives extra work.
Pick off the sprocket and lay down the wheel with the braking disk upward on a piece of board. Cover the bearing with a rag.
Loosen the valve ring (and brace bolt).
Press the tyre from the rim. Indeed this is about the only way it works - the heavier the boots the better.
Knees on the tyre and tyre irons at the other side to work the tyre from the rim.
Remove the tube. The wheel remains well balanced if you let the tyre on the rim. You could also mark the position of the valve on the tyre. With real knobblies balancing is not necessary.
Remove the sting and check the tyre for further dameage. Feel the inner side with your fingertips.
New tube with some air pumped in is put intu the tyre. Watch the valve being placed correctly.
Put the tyre back on the rim - start at the valve. The tyre should be pressed from the rim now and then (as done at four) to make extra space to put it on the rim again. Don't puncture the tube with the irons.
Inflate the tyre to its right pressure. See if the tyre is parallell to the rim and the tube does not stuck between rim and tyre. The wheel is ready to be mounted again.
Push the front suspension firmly for a few times before tightening the clamping screws. This prevents the axle from being mounted out of position. With the rear wheel the axle needs to be pushed against the chain tensioners. This can be done by pushing the wheel forward with one knee while tightening the collar nut.