Post in forum #235250 - Obtaining the highest-resolution images from Tumblr

Munkelzahn said:
Search for the image with Reverse Google Search.
If you're lucky, someone has reposted it, and you can get the direct image link that way.

please make the posts you listed clickable

Also, if the artist had some text in their post such as a description or whatever, you can google search that and find reblogs that are still intact. This has helped me a few times.