I have found only Load C no Load E 10 ply?

It may be because all hd brakes won't fit inside a 15 inch wheel. 16 inch is the smallest I've ever seen on a 3/4 ton.

What???? 15" wheels fit just fine with a little
Just take a little off the ears of the calipers and 15" bolt right up to any GM HD up to 1 ton i have seen.
And yeah it is the sidewall issue why they don t make a E type 12.50x 35x 15. With that much sidewall. Heat can be an issue and cause a blow out.
I am sure they could build an E rated 35x15 but they would cost high $$$$