2003 Ford Explorer

Noises problem
2003 Ford Explorer 6 cyl All Wheel Drive Automatic 57000 miles

I have a 2003 Ford Explorer XLT 4.0 FF with 57k on the clock. I have began to notice that when cruising, or when I am not on the throttle and free wheeling, the truck makes a howling noise, somewhat rythimic (rotational I believe). I have checked my front brakes and cleaned them, this has done nothing but dirty up a set of clothes. I have read tat it can be many problems, but I do not want to go and spend money without knowing what it is. Also, when the truck has been driven a bit, there seems to be a thud, again rythmic in nature. I have read that the rear end may be a problem, but I feel it to be the front. Bearings? Fluid issues? Also note, the tires on the front are dissimalar by the following numbers (245 65 R17, 105S, M+S and 245 65 R17, 105S, M+S, DT) Please help!
October 3, 2008.

Have you checked the tires for minor cupping? If the tire tread is uneven it will cause the problem or you describing.

Oct 3, 2008.