If your tires have been stored for an extended period in the vertical position, you may never be able to get the flat spot out. Always store bias ply tires laying flat on their sidewalls, not upright on the tread.
Re Coker Tire: I have gotten more than one set of defective tires from them, but they were excellent about replacing them.
If you do revert to radials, make sure to use a radial tube, specifically made for use in a radial tire.
