For what it is worth concerning bias vs radials: I replaced my 900x14 bias plys with 235/75R15 radials when I went to disk brakes on my F. I selected the 235's because the math showed them to be virtually the same diameter as the bias ply's. On a trip to Phoenix last January, I measured my odometer reading for a 10 mile stretch of mile markers. The reading was within 1% of the reading I got on the same stretch the previous year with the bias plys. Dan Reitz Northridge, CA [Non-text portions of this message have been removed]