Stop in for a cup of coffee

I found a set of 15x7 original police steelies that I am picking up this weekend, so next week i can work on having new tires mounted. I like the stink bug stance so i am looking for recommendations on what size tire I can put on the rear to give her a little boost in the caboose.
I assume there are some differences between our cars when it comes to fender lips, and I am running the SS springs, but I have 15x8.5 with 3.25 BS and a 295/60-15 Hoosier. The older pic with the black wheels were 15x8 with 4" BS and 275/60-15 Firestone

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