1990 454 ss wheel backspace offset

[fredscarryall]

I just bought a 1990 454 ss truck with 63,000 miles. I am putting a belltech 4/6 drop kit and 20" rims. Here is what I know. Everyone is talking about the front rim they use is a 20x8.5 with a 5 to 5.25 backspace and the tires they run are a 245 45 20. People are running a 20x10 in the rear with a 295 40 20 tire. But no one had said anything about what rear back spacing they are running. Does anyone know the rear back spacing they are running on there 20x10 rims. I want to avoid roller the rear fender.