Hy stouchton and guys, those wheels look like three piece wheels to me. Stouchton with the wheel in position with the white ring facing up remove the valve core from the tube and let the tire deflate completely, once the tire is deflated, push the tire bead down anyway you can, it could be difficult to get it to go down. Once you get the tire bead down the white ring can be knocked down toward the tire if it didn't follow the tire bead down, once the white ring is down it should reveal the locking or keystone ring, that ring should have a split somewhere on it, that split can be pried open and up and off the rim. Once the keystone ring is off the wheel the white ring should lift off the wheel and the tire should be able to be removed once the opposite bead is broken, hope that helps.
