Whiskerbruce- I did some online surfing myself for 7.50x17 tires. Seems as though the STA and Tornels you found are about it for that size. everything else requires a wider rim. Even Interco (Super Swamper maker) has nothing that narrow.
I have found a radial LT235/80/17, it requires a 6" minimum rim, just food for thought. There's a number of different companies that make them.
