160 MB are tiny images for 9. Using 176.4 I've been adding rtree indices to images that are over 30 GB each.
But, you didn't answer my question... are you working with read-only images?
It's most likely something simple like that. To help you find the problem, we need to know everything you are doing, every step of the way starting with the original TIF file you have, how you import or link it, exactly how you are trying to add an rtree index, and so on.
It also helps if you post someplace where people can download it an example of a TIFF file with which you have trouble. Then people can repeat your workflow step by step.
For example, using 176.4 I just imported an NAIP TIF file that's about 440 GB. Here's the schema, complete with rtree index: