I own a 1999 F-150 4x4 with the 5.4L engine. I am having considerable vibration when braking at low speed and during slow, controlled braking. I had the front pads replaced at 30,000 miles and the rear pads replaced at 45,000 miles (am at almost 50,000 miles now) and I have had the tires rotated and balanced three times in the last six months. The balancing sometimes works for a short period of time and then the problem returns. Three different repair shops have found nothing wrong with the braks. Before I spend $500 on new tires (my Goodrich Long Trails still have 20,000 miles left on them), I want to know if anyone has any suggestions. I found a technical service bulletin regarding brake vibration - should I obtain this, or is it for drum brakes only? Thanks.