Tire Size vs. Rim Width

Regardless of my smart *** comment, what are you trying to accomplish? Do you just want the look of a skinny tire or do you have a fitment issue? Sound like you have a 15x8 rims for the front. What car are we working on? A bodies all vary in wheel/tire fitment between models.
Probably changing the look up, while saving money (like the rest of us) for new rims