OK that makes sense forgive my ignorance....
So if that is the case now why does places like Les Schwab who sell the Toyo tires sell them as "better" than 10 ply tires because they are 11 ply. Seems just a play on words now. I always liked the KO tires but the Toyo has a warranty and are sold as 11 ply so I was going back and forth.
I was also interested in the Duratrack tires but read that they were 3 ply E rated tires so I stayed away from those. I guess marketing and advertising 3 ply "rated" as 10 ply is just the norm now days
Which tire are they claiming that for? They're probably counting the SW plies plus the tread plies. Not all Toyo tires are "better", for instance the Toyo AT II in 285/75r16E is a 2 ply Sidewall tire where the KO2 is 3 ply but the Toyo AT II in the next size up 295/75r16E is 3 ply sidewall. Toyo and Nitto tires are size specific for number of plies for AT II and Tera Grappler G2, Toyo makes both BTW. All Toyo MT tires are 3 ply sidewall. See for yourself:
Specifications | Toyo AT II Tires
Specifications | Toyo MT Tires
Even if I add the tread plies plus the SW plies for the Toyo MT or RT (their tougher tires) it adds up to 10, the AT II in most E sizes add up to 7 or 8.
E rated now really means the tire design can handle 80psi for widths 295 and smaller and 65psi for widths 305 and larger. D rated is 65 for 295 or smaller and 50psi for 305 and larger. This is regardless of how many plies are in the tire.
Guys who haul heavy loads, like me

, prefer E rated tires with 3 ply SWs over 2 ply SWs. I've run both with 4500lbs in the bed and there's a noticable difference. I've never paid as much attention to the number of tread plies though.