Sara, I hear you! I also have small hands, but it is true that there are just some tire/rim combinations that are much tougher than others. I have struggled with tires at that last 3 inches, given them to my large-pawed, muscular, bike mechanic BF and watched him struggle also! He will, however, eventually get them on!

I sometimes find it easier to turn the wheel so the side I am putting on is away from me and using my whole hand and fingers to roll the tire on. I have a bit of arthritis in the thumbs and they just don't have the strength to do the job sometimes.