Hmm, let me plug into your formula Clyde .. it will take awhile because I have to convert to kg. .. (crank grind crank) .. It looks like I end up at 40mm there. I think my formula is better for me, from experience I like 35-38mm tires the most. My formula is winning!
I think we can declare my formula the best gravel tire width formula ever invented based on the data in so far..