wheel bearing or u-joint? explorer sounds like a helicopter when driving.
You really need someone to check this out, ASAP.
Wheel bearing, there are inner and outer. The outside one is the one that keeps the tire attached to the car. They will blow out and the tire will come off while driving. If it is really bad, you would be able to wiggle the tire back & forth while parked.
U-joint, there is a front and back. Again, if it breaks, you drop the drive shaft even while driving. The front one can cause the car to flip while the back one just drags. If bad, you can wiggle the drive shaft. Also, replace both even if only one is damaged because the other one will usually go out in a short time.
I've had a wheel come off and dropped the back drive shaft. I was lucky because I had both my daughters in the car, both times!
