I have the Ariat Bromont insulated boots and they're a "full" calf width, I usually take about 16/17" calf widths on tredstep chaps, dont know if that helps??
ride- away catalogue have calf widths included in description of boots.Dont know your size but in catalogue size 5 1/2 to 8 1/2 vary from 17.2 inch to 17.9 inch