Humming or buzzing is usually caused by a noisy wheel bearing, however, your vehicle doesn't use the design that is prone to developing this problem. Bad tire wear patterns can cause noises too but of all the wear problems, the one that causes noise will affect both front tires equally. An inspection at a tire and alignment shop will identify that. Ford has had real bad tire wear issues that can't be corrected since the early '80s, but that mainly affects their trucks and front-wheel-drive cars. The Explorer is one of their few vehicles that don't have this problem. Tire wear problems on yours will be due to worn parts and / or misalignment, not poor design.
Visit a tire store for an inspection. They'll be able to identify the cause of the noise.
Thursday, June 19th, 2014 AT 10:25 PM