2004 Ford Explorer 6 cyl Two Wheel Drive Automatic 56000 miles
I have a Ford Explorer Sport Trac that has been a wonderful truck until the last few months when I have noticed a rumbling noise which seems to come from the front passenger side wheel area. Sounds worse at low speeds and when braking. Also found out that both front tires on the inside tread have wear that is uneven with the tread sort of " cupping" on the tread. But only on the inside of the tires. No issues with the rear tires at all. I suspect a bad wheel bearing on the passenger side wheel but don't know why the tires have worn that way. Any ideas as to what all needs to be repaired?
Hi purpleraider131. Welcome to the forum. What you're describing doesn't really sound like wheel bearing noise. I suspect the noise is from the tire wear. Two things will cause uneven wear on just the inside edges. The first is excessive negative camber. That means the tire is tilted in on top as viewed from the front or rear. Camber can change on just one wheel without affecting the other one, but Ford had a huge problem years ago with their twin I-beam front suspension. The only good thing that can be said about it is it was tough. Tire wear was always a very big problem, more so on the right front. Further, as the front coil springs sagged with age, (as all springs do), the tires moved up and pivoted on the I-beams which lowered camber. There are repair kits to adjust that alignment angle but it is a very involved repair that isn't done unless absolutely necessary. The easier repair is to replace the springs. If you have the twin I-beam yet, have the ride height checked.
I think long before 2004 Ford switched to the much better upper and lower control arms. They aren't as strong but they give a much better ride and weak springs have less affect on tire wear.
The second thing that causes wear on the inner edges is excessive negative toe. That means the two front tires are steering away from the center, (the fronts of the tires are further apart than the rears of the tires). Even if only one tire is misadjusted, it affects both tires equally. The wear takes place on the leading edge of the tires. If you exaggerate it for clarity, imagine the right tire is turned 90 degrees to the right and the left tire is turned full left. Now it is easy to see that the inner edges of the tires are in front. They are the part of the tread closest to the front of the vehicle. Now take a pencil, hold it straight up with the eraser on the desk top, and slide it sideways. The eraser will bend, the leading edge will scrub off and make eraser crumbs, and the trailing edge will actually raise up off the desk top. All the wear takes place on the leading edge. That's what happens to the tires when toe is too much negative. When something causes toe to change on just one wheel, that will make the tire steer that way. You have to correct by turning the steering wheel. That makes the misadjusted total toe, (two front wheels measured together), split evenly to make the vehicle go straight, but the steering wheel will be off-center.