You have a Grand American Tire in Simi.
http://grandamericantires.com/catalog/tires
I tried to link to the 16.5 tires, but it didn't seem to work. Enter tire size using " - " for ratio
I was looking for 16.5 tires a couple years ago. The 9.50 Firestone TransForce would have worked on the front, but I had aftermarket slotted aluminum with wider rears and needed something like 12.0 x 16.5.
You can find 8.75 and 9.5, 16.5 tires, but above that is the big mudders as you have found.
I bought 17" Hummer wheels and still had trouble. I wanted 265 front, 285 rear, E rated in a name brand. Bridgestone Dueler was the only one that could give me what I wanted. All the other companies could only give me a D rated for the rear. The new tires ended up being a little larger in front and a little smaller in the rear than the old tires.
Sorry, I've wondered. Nothing there that applies to your question.
If the Grand American in Simi is like the others, call and tell him what you are looking for. He will give you a lower out-the-door price over the phone than if you just drive in. If you phone he knows you are still shopping and he wants your business.