Napkin math/free body diagram of stresses in the hub flange: The class's obsession with lowest possible offset/widest possible track width, and the HEIGHT of the tire, is likely doing more harm than the difference in "stickiness" between RA-1s and Hoosiers. The added unpsrung weight isn't helping, either. I actually think the "stickiness" is probably the least important of the four, for this particular failure.
Long-term, SM would benefit from less tire, not more.