Start moving the tires around on your car and see if it moves the thumping. A bad tire may be intermittant and may make a thumping noise that seems like an axle halfshaft. (BT, DT). Bearings may get loose and worn out. How long they last tends to depend on climate. In drier parts, the life of the car is not uncommon, 300-500Kmi. In wet climates where snow is common, less.

-brian

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Brian Toscano