In Unity 5.6, sprite tiling is revamped. But at first I had troubles getting the seams between the sprites correctly.

SETTINGS!

After fidgeting around in the settings a little, I found another developer who had the same problem as me. While his final answer didn’t help me, it set me on the right path. The problem was that I had Bilinear Filtering enabled for my texture. That meant that the edges were blurred, resulting in a seam. When I changed the texture setting to Point filtering, the seams dissapeared.

Filter settings