After putting 2 new tires put on my 2004 Explorer I started intermittently
experiencing a bumping (or thumping, or slipping) feeling that seems to be
coming not from the tires but the transmission or around the differential
(however, I do not know enough about cars to accurately pinpoint it). I
took it to the local dealership and they told me that it might be that the
Explorer senses the difference in the tread two sets of tires and this
might be the cause. They suggested that I replace the two older tires with
the same as the new ones. If that doesn't work they said that they received
an "alert" from Ford about frequent repairs of the driveshaft (or something
like that). The problem that I have is that the two new tires that I have
are no longer being produced and to acquire two additional ones is
impossible. So, to test out the first theory will cost about $400.

My question is, does anybody have any thoughts on what the thumping or
bumping could be caused by?

Thanks,
Bob
West Virginia