Need help with tire size

[ZMAR]

I have measured and remeasured to get the exact wheel I wanted on my 71 swb. Came up with 20x8 in the front w/ a 4.5" bs. Rear is 20x9 w/ a 4.5" bs as well. My truck is bagged and lays the front cross member and lays the frame in the rear. My wheels are being made so I don't actually have them yet. I was seeing if someone had a similar set up and what size tires they are running. I was thinkin 255/40 up front and hopefully I can fit a 285 or 95/40 rear. No inner fenders front or rear. Any ideas? Thanks in advance