I'm willing to bet that during jounce/rebound there's some contact somewhere, during normal driving, there's a lot of forces happening all at once, spinning tires, large bumps while spinning and turning/steering...what do your bumpstops look like?

I had a similar problem with some Coopers, problem went away after my steering and suspension upgrades. What suspension and steering setup are you using?

 

I have a 6.5 in RC lift and the cavfab crossover steering, but I'm sure the tires got cut or cracked with the stock steering.

 

Long arm? Over or under knuckle steering/trackbar? Bumpstops?