Ball Joint problems of the 2004 Ford Ranger

We noticed extreme tire wear on the Rangers front tires, which at the time had 7840 miles on it. I immediately took the vehicle to bay harbor Ford. The service person explained that the tires were only warranteed for 12 months or 12,000 miles. On April 27th , I arrived early and spoke to the service manager, mr. Jim basilotto. He looked at the vehicle and agreed there was an alignment problem. I explained that the vehicle is garage kept and it is only driven back and forth to work on the local roads. The vehicle has never been off- road or even on bad roads and never traveled farther than port charlotte, FL. She or I can not ever remember hitting a pothole that would come close to causing a problem. The service people put the car on the lift and checked the tie rods by trying to wiggle them while the vehicle had its full weight on the tires. ( I personally check front end parts by raising the wheels off the ground and check for play in the ball joints also) the tire pressure in all 4 tires was low (lower 20 psi) and they added air. Again the tire pressure is as it was when it left the showroom. It is our conclusion that the alignment problem had to exist when we left the dealership with the vehicle and should be covered under the warranty. In comparison, my 2001 explorer has 53,000 miles on it and the tires are in great shape. It has been off road on many occasions, through the worst bone jarring potholes on the cross bronx expressway and never had any alignment problems. I now have to pay to get a wheel alignment and a new set of tires for the Ranger and it only has 7845 miles on it. I feel that the dealership should have covered the tires and alignment under the 3 year , 36,000 mile bumper to bumper warranty.