There are probably multiple ways to diagnose bad hub bearings. You should hear a humming noise going straight. In a curve at high speed as you turn the wheel in one direction the humming noise should go. If turning right and the humming noise goes away, you have a bad left hub bearing. This is due to less load on the left hub as you turn right. Same applies in for the right hub. The second and sure way to diagnose a bad hub bearing is to jack up both front tires off the ground. Grab the 3 & 9 o'clock positions of one tire and rock the tire back and forth to see if there's play in the tire. Also grab the 6 & 12 o'clock position of the tire and rock the tire and check for play. If there's any play while you move the tires, you have a bad hub bearing. I use this method to determine a bad hub bearing on my 05 4Runner. Although only one is bad I end up replacing both. I bought pre-assembled hub bearings from some one on this forum. It costs $170 shipped for each side.