When I took it to the local Toyota dealer, the guy at the counter only looked at the driver's front and declared that I needed new tires. I explained that I'd like to know what caused the noise. He said it didn't matter and that they would not consider a rotating the tires.

I went across the road to a tire dealer. They mounted four (4) Michelins and told me my TCH really needed alignment.

I suppose I should have "reminded" the dealer to check alignment EVERY time I took it in for the usual 2,000 mi. rotation.