I have a 2016 Diamondback Release 1. I had the same problem removing a tire from the rim so I took it to my LBS. After fixing it, the mechanic said that it took 2 people at the shop to remove the tire from the rim. They put the wheel over the rim of a large round trash can to work the tire loose. The Schwalbes that came with my bike have a wire bead that conforms very tightly to the inner part of the rim. Realizing that I would be stuck if I needed to change a flat on the trail I decided to switch to a different tire. I ended up cutting the Schwalbes off of my rims (including wire snippers for the beads) and replacing them with foldable Maxxis tires. There was a silver lining: in the process of doing this I switched over to a tubeless setup (the valves were included when I bought my bike) which made a significant improvement in bike acceleration and which has saved me from flatting after encounters with thorns.