On my 40 Ford when I was trying to get an idea if the wheel and tire combo I thought would fit in my wheel well...... I made a wood model out of ply wood and thin card board/poster board. I found a tire the size and width I was planning on using and measured it with a wheel mounted and inflated to the proper specs. I took those measurements, and made 2 ply wood circles. I drilled the bolt pattern on one. I used 4 2x4's to go in between them, and screw the plywood circles to the 2x4's. Bolt the one on your axle. Cut the poster board and then place it over the plywood circles and staple it on there. On mine I tried to mimic my wheel off set and the poster board actually hung off the inner ply wood piece. I cut the outer piece of plywood in the center so I could get to my lug nuts. My out come is still unknown because I decided I had too many variables to guess off of. I'll have to put the body back on the frame, put the fenders, and then do real world measurements. Hopefully by the time I get to this, they stil make the wheels I went with. I already purchased the fronts. Haha