Start tyre removal at the valve undo the locking ring that holds the valve and screw it up to the valve cap so you can push the valve and inner tube away from the rim then insert the tyre levers DO NOT PUSH THEM IN TOO FAR. Fit the new tyre on the rim (check tyre rotation direction) then talcam powder all the inner tube, put it in the tyre then add enough air in the tube to give it some shape. Starting opposite the valve, lever the tyre on evenly in small increments keep checking around the rim for the tube trapping between tyre and rim. when it starts to get hard to lever the tire on release the valve so air can be sqeezed out, for the final ten inches of tyre ensure the tyre is in the well opposite the valve and finish fitting at the valve with the valve pushed in as far as possible the lock ring will stop it going inside the rim, this stops the tyre and levers trapping the tube. DONT RUSH IT.