A tenured position with less pay and less responsibilities than a professorship At the moment I am a (soon to be graduating) PhD student. The reason I went to graduate school is that I love doing research. In graduate school I discovered that I absolutely hate teaching but I had to do some of it to avoid starving to death (though I tried to do a reasonably good job since I recognize it is not the students' fault that I hate teaching).

I know there are some teaching-free postdocs at R1 institutions. They can be rather difficult to get but my discussions with some senior people seem to indicate that my publication record could get me such a postdoc. However, teaching-free permanent academic positions seem to be much less common (in my field, there are places like IAS, IHES and some smaller institutions, it seems almost exclusively in Europe).

The question is is it possible to "downgrade" a normal professorship at an R1 institution (in US) in the following way: I don't have to participate in any administrative or teaching activities, I have tenure and I get paid less (say, 65% less)? I think I still could survive on such a salary. I am afraid to ask senior people I know about this since this kind a question conceivably might worsen their opinion of me.
I’m sorry to disappoint you, but at US R1 universities, a position like the one you imagine doesn’t exist. To have a job with tenure at any salary, you have to teach and do some administrative duties.

If you win a Nobel prize or move to France on the other hand, the possibility of you getting a tenured research-only position may become more realistic. See this question for more details.