You sure you don't have any loose lug nuts? Could also be wheel bearings, ball joints, tie rod ends. Lift it off the ground about 2" and stick a bar under the wheel and your hand on the tire at 12 oclock lift up and down for movement and inward and outward. Also check tie rod end play by hold the tire at 3 and 9 oclock and move side to side...look and feel for the least amount of freeplay. Wheel bearings tend to make more of a humming sound and change sound when you turn...so if you hear more sound making a right turn, then its likely the left wheel bearing...and if its more sound when you turn left, then its a right wheel bearing.How is the front breaks condition? any pulling when you break, or pulsating in the pedal? Front end problems are not hard to detect if you look closely, and have someone else do the tire movement checks. Bad caliipers could also be a problem...so check it out closely. If you still can't locate the problem...take it in for front end check.