I've started to notice a very slight vibration I can feel when coasting. Seems to have come and gone in the past few weeks, but I noticed it again this morning. The vibration quickly comes and goes at very regular intervals that I might correlate with wheel rotation -- a slight friction of some sort. Again it doesn't seem to do it all the time.

These are some used steel (Toyota OE) wheels I run in the winter.

Does this seem familiar to anyone? Perhaps the start of something I should investigate?

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02 Taco 4x4, V6, TRD