Now you mention it, I think the SM would look seriously mean with some Jumbo sized rubber mounted on each corner, but at 1lb each, they arent light wheels/tyres. Thats what makes my poor HvMaxx's life so hard, trying to gear for a 12lb truck isnt as simple as with a powerful Neu/lehner motor. That said, you should get there in the end.
As for the sticky drive line, I would say remove the tranny, then spin the front and rear wheels by hand to see if either is a bit rough/sticky etc- the wheels should spin down nice and gradually, not abruptly. You've stripped the thing down so many times it should be second nature by now I reckon....
