The radial bulge I was referring to is where the tread meets the road. Compared to bias ply, common radials always look like they're going flat a little. I don't think you'd get that due to the way the tires are made to look like bias ply with an inward taper at the outer edge of the sidewalls.
My Packard has 4.5" rims and I do see that the sidewall is a little more rounded than flat but it isn't really noticeable and the tires seat in the bead just fine. I would speak with the DB people about it. My tires are 700R16.
