Carrier bearing noise

My 2002 Honda Accord V6 with automatic transmission & 90,000 miles started making a mild,rhythmic, thumping noise when cruising @ 45mph. The noise disappears (or becomes indistinguishable from road noise) at highway speeds (65 mph). My mechanic suggested a tire problem or a carrier bearing problem. I had the tires (1-yr old Michelins) checked out at Costco where I bought them…no problem. Carrier bearing problem sounds expensive. Any suggestions as to what may be causing the noise and/or actions I should take?

Your Accord doesn’t have a carrier bearing. A carrier bearing is the bearing that holds the rear of a driveshaft just forward of the second universal joint, like you see under the big trucks. I suspect he might have suggested a CV joint.

Two points:
(1) the wheels should be spun on a machine that does “road force balancing”. That can detect internal tire anomolies that regular balancing cannot.
(2) the only way to determine the condition of the other possible sources is on a rack. I suggest you take the car to a reputable chassis shop.