I have been running 29.5x10.5x15 Mickey Thompson ET drags on a 7" wheel for years with no problems at all. I get a good contact patch and even wear across the entire tread. I wore the last set to the cords and they showed the even wear very well!! I would have liked to run a wider wheel, but a stock wheelwell, stock spring location, and no money prevented it from happening. I would think a 29x9 would work fine, even a 28x9. It may not be optimum, but with tire pressue adjustments you should have good results.