Irregular (cupped) tire wear

I have a 2007 Honda Accord with 56K miles. The rear tires have about 16K miles on them and have become cupped on the inside edges. They were put on the back (new) and were not rotated until recently when the road noise increased to the point that I had them checked.


Alignment is good on all wheels
No obvious problem with bearings, brakes, shocks, etc.
The previous tires (same brand) were new with the car and lasted 40K miles on the back with no rotation and no problems.

Is there any history of the tires themselves being the cause of the problem? Does anyone have any suggestions?
I have cross rotated them to the front with the hope that the cupping will even out with additional miles. Is that reasonable?

Probably a worn or possibly bent suspension component. Also, I would suggest rotating every 3,000 or 6,000 miles. If you have a bent or worn suspension component alignment will not fix the issue.

I'll second the worn or damaged suspension scenario. Could be the struts, a worn out end link bushing. Visual checking is difficult...sometimes a road test with a chaser car is needed to see what is happening back there at speed. If it is the same wear on both left and right, then I'd be more suspect of a bad cross link component. Struts tend to fail one at a time.

The easiest, though not always reliable, is the bounce test where you push down on the rear of the car and see if the car rebounds without bouncing.

Next, look at the strut tube bodies for signs of oil leakage...oil stains, or collected oily dust.

Then check all the stabilizer links for bends and the bushings for end play. You've already mentioned the car's been tested for alignment, I'd also check for wheel bearing play and brake drag.