Cragar SS Wheels 15x8 4.250 backspace

i just brought home my new wheels and tires. I went with the keystone Klassics because I love the black insert with my black car. Anyways, I have a 15x8 with 3 7/8 backspace for the rear. I have a 255/60r15 on it. The fronts are 15x6 with I think 3 1/8 backspace. Got a 215/60r15 there. I just set them next to the car at noon and I'll be surprised if I can get that 255 under there.....that's a big tire! BTW....4 1/2 inch bolt pattern