I am running BFG 315 tires with the stock rims. I have Rancho 9000X shocks... new. I am getting serrious vibration... the rear drivers side tire is jumping after hitting a bump in the road going about 60-70. The rear shock was bad and I had a new one put on and it's started doing it again. Had the tires balanced 4 times at Discount Tire... any ideas??