Redline,
As long as the carcass size is the same (e.g 255=33") then the treadwidth is something they should be able to control. A 275/85r16 could be made from a 315/75r16s carcass.
I also contend that those coming over to buy these tires are gonna be your atuned tire customers and would understand variations in sizing and not necessarily be looking for the most popular size. I mean, with a due respect to TreadWright but I don't see them selling tires to the "masses," rather those looking for a deal on an MT. The masses will still head to Costco/Sams/Walmart/Discount/&c