Can I change from a 26 x1.95 tire to a 26 x 1.75 tire on the same rim?
All roads lead to sheldon on this one... here is another question that discusses this issue in converse (how wide in this case).  In reality, the OP did not provide any ISO sizing data for the 2 tires nor the rim, so can't really answer. (but tentatively, yes, it should work fine)  How wide of tires can I run on a Victory Vision road bicycle?