Can 15x10 with 275/60r15 or 295/50r15 fit on a stock frame 1986 Monte Carlo and if so what backspacing should you run?

 

Yes it can providing your not trying to fit the tire inside the wheels well. I believe stock backspace is 3.5 or 4 inches, if you keep it factory size there should be no issues. Probably best to measure what you currently have and check how much room you have before buying a set.