Here's how Unity's default sprite slice handles all the road chunks: https://imgur.com/a/NRp4YxM
You can tweak it so it includes a larger border, but then you have gaps between your tiles you have to hack around.
More importantly, there are inconsistencies in size even among things that should be on the same grid. For example the sidewalk_chunk is 89 pixels tall when sliced to remove all transparency. This has the same not-divisible by 2 issue, but it's also 4 pixels taller than the road chunk. So putting them on the same grid doesn't work well.