We have a consistant vibration in the passenger seat that can also be felt in the drivers side. We rotate the tires every other time we change the oil at 3000miles; we now have 18,000. We have asked the dealer about this since the first 500 miles. We have had to pay for the rebalancing everytime we rotate the tires. The dealership blames the Pirelli tires and says they are out of round and of course Pirelli is no help except to sell us new tires for prorated cost. I keep wondering if this really is the tires. Any answers or advice on a new direction.