I am planning another build (like always) and I want to use a 24 X 3.0 rear tire with a 26 X 2.125 front tire. I want to find the tallest 24 X 3 available so that the diameter front and rear match as closely as possible. I have measured some Felt thick bricks that I have and they are 25 1/2" to 25 9/16", most of the 26's that I have are between 26 1/4" and 26 1/2" tall. I know that is not a big difference, but if anyone knows of a taller 24" tire, that would probably be the tire I would use.